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MANAJEMEN KESUBURAN TANAH Dikoleksi oleh : Prof.Dr.Ir.Soemarno,M.S. Jurs Tanah FP-UB --- PSLP PPSUB September 2013 MANAJEMEN KESUBURAN TANAH Dikoleksi.

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Presentation on theme: "MANAJEMEN KESUBURAN TANAH Dikoleksi oleh : Prof.Dr.Ir.Soemarno,M.S. Jurs Tanah FP-UB --- PSLP PPSUB September 2013 MANAJEMEN KESUBURAN TANAH Dikoleksi."— Presentation transcript:

1 MANAJEMEN KESUBURAN TANAH Dikoleksi oleh : Prof.Dr.Ir.Soemarno,M.S. Jurs Tanah FP-UB --- PSLP PPSUB September 2013 MANAJEMEN KESUBURAN TANAH Dikoleksi oleh : Prof.Dr.Ir.Soemarno,M.S. Jurs Tanah FP-UB --- PSLP PPSUB September 2013

2 KESUBURAN TANAH Kesuburan Tanah merupakan kemampuan suatu tanah untuk menghasilkan produk tanaman yang diinginkan, pada lingkungan tempat tanah itu berada. Istilah lain yang maknanya hampir sama adalah “produktivitas tanah”. “Kesuburan tanah” berhubungan dengan ketersediaan hara dalam tanah. Produk tanaman dapat berupa: buah, biji, daun, bunga, umbi, getah, eksudat, akar, trubus, batang, biomassa, naungan, penampilan dsb. Tanah memiliki kesuburan yang berbeda-beda tergantung sejumlah faktor pembentuk tanah yang merajai di lokasi tersebut, yaitu: Bahan induk, Iklim, Relief, Organisme, atau Waktu. Tanah merupakan fokus utama dalam pembahasan ilmu kesuburan tanah, sedangkan kinerja tanaman merupakan indikator utama kesuburan tanah. Sumber: ….. Diunduh 15/3/2012

3 TANAH SUBUR Ciri-ciri Tanah Subur: 1.Kaya unsur hara esensial yang tersedia untuk pertumbuhan tanaman, termasuk nitrogen, phosphorus dan kalium. 2.It contains sufficient minerals (trace elements) for plant nutrition, including boron, chlorine, cobalt, copper, iron, manganese, magnesium, molybdenum, sulfur, and zinc. 3.It contains soil organic matter that improves soil structure and soil moisture retention. 4.Soil pH is in the range 6.0 to 6.8 for most plants but some prefer acid or alkaline conditions. 5.Good soil structure, creating well drained soil, but some soils are wetter (as for producing rice) or drier (as for producing plants susceptible to fungi or rot) such as agave. 6.Beraneka-ragam mikroba tanah mendukung pertumbuhan tanaman. 7.Topsoilnya cukup tebal. Sumber: ….. Diunduh 15/3/2012 Fertile soil has an abundance of plant nutrients including nitrogen, phosphorus and potassium, an abundance of minerals including zinc, manganese, boron, iron, sulfur, cobalt, copper, magnesium, molybdenum, and chlorine and an abundance of organic matter. In addition, fertile soil has a pH ranging from 5.5 to 6.2 and good drainage. (http://www.ecochem.com/t_faq8.html) Tanah Subur

4 SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, Lack of soil fertility causes decreased yields but many plant diseases are also related to poor soil fertility. If the soil fertility is not good, the crops are not in optimal condition, and are thus more susceptible to diseases and pests. The presence of diseases and pests lowers productivity levels, again threatening further the livelihoods of the rural communities. Such conditions can be avoided by improving the condition of the soil. Sumber: journeytoforever.org/farm_library/AD2.pdf….. Diunduh 15/3/2012 The presence of organic matter in the soil is fundamental in maintaining the soil fertility. Organic matter in the soil consists of fresh organic matter (leftover of dead plants and animals) and humus. The fresh organic matter is transformed into humus by soil organisms. Humus gives the soil a dark colour and can retain a lot of water and nutrients. The first step in maintaining soil fertility should be directed at maintaining the organic matter content of the soil. This can be done by using appropriate crop husbandry practices and by applying organic manure or compost. If the soil is very deteriorated, applying chemical fertilisers might be necessary. Chemical fertilisers can restore the soil fertility very quickly; because the nutrients are available to the plants as soon as the fertilizers are dissolved in the soil. It takes much longer before organic matter is transformed into humus and has released its nutrients.

5 Crop husbandry measures Crop husbandry measures refer to methods the farmer can use before, during and after the growing season that do not require the addition of a new component to his business nor the purchase of many extra inputs (just sowing or planting materials). These measures include mulching, green manuring, intercropping, green fallow periods, and agroforestry. All of the above methods are intended to achieve and retain optimum conditions in the root zone, where the crop gets the nutrients and moisture it needs for good production. Also the soil must be penetrable for plant roots. Methods such as mulching, intercropping and agroforestry aim to keep the soil covered in order to prevent evaporation and dehydration. Intercropping and agroforestry also ensure that extensive root systems are present in the soil; planting different crops with different root systems that need different nutrients contributes to a better utilisation of the available nutrients and water. The trees that form a part of agroforestry systems also ensure that the nutrients in deeper soil layers are utilised. Green manuring and green fallow periods contribute particularly to a higher level of organic matter and to greater availability of the nutrients that are released from the organic material worked into the soil. The latter function can be intensified if leguminous plants are used. SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, Sumber: journeytoforever.org/farm_library/AD2.pdf….. Diunduh 15/3/2012

6 BAHAN ORGANIK TANAH Organic matter is very important in soil fertility management because it has many properties that help increase soil fertility and improve the soil structure. Organic matter has a great capacity to retain nutrients; this is especially important in sandy soils, which retain very few nutrients. Organic matter can also retain a lot of water, which means that in dry periods more water is available for the plants for a longer time. This is especially important in sandy soils, which retain little water. Organic matter can improve the soil structure. This is important for both sandy and clay soils, because they have a poor structure. Finally, organic matter stimulates the growth of soil organisms, which help make the nutrients in the organic matter available to the plants. The organic matter in the soil consists of fresh organic material and humus. Fresh organic material is plant and animal waste that has not yet decomposed, such as roots, crop residues, animal excrement and cadavers. The fresh material is transformed by soil organisms into humus, which is also called organic soil matter. In the process, nutrients are released; organic matter thus makes nutrients available to the plants. SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, Sumber: journeytoforever.org/farm_library/AD2.pdf….. Diunduh 15/3/2012 Humus, i.e. organic soil matter, is material that has been broken down so far that the original fresh material is no longer distinguishable. It gives the soil a dark colour. Humus itself is also broken down by the soil organisms, which releases even more nutrients, but this process takes much longer in cold or dry conditions. HUMUS

7 BAHAN ORGANIK TANAH Crop husbandry that contributes to a positive balance of organic matter is the basis for good soil fertility in the long term. The balance of organic matter must be even or positive, that is, the amount of organic matter that is added must be equal to or greater than the amount that is broken down and thereby lost. However a positive balance of organic matter is difficult to achieve. This means that if a lot of organic matter is lost (by erosion for example) it is difficult to increase the level of organic matter in the soil. Even in favorable conditions and with good crop management, this can take a number of decades, especially if during that time crops are grown that are almost completely removed with the harvest. The rate at which organic matter is broken down depends largely on the climate. In warm, damp conditions the organic matter is broken down faster than in cold or dry conditions. SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, Sumber: journeytoforever.org/farm_library/AD2.pdf….. Diunduh 15/3/2012 Cover crops are gaining favor as a way of increasing organic matter. Winter cover crops have been used for years, primarily to protect soil from erosion. Winter cover crops can also take up much of the nitrogen left over at the end of the growing season. Winter rye has been an old stand by. It can germinate and make quite a bit of growth, even if planted as late as October. Winter rye is efficient at taking up left over nitrogen. It remains green over the winter and resumes growth early in the spring. It adds little organic matter if plowed under in early Spring while still small. If allowed to grow until late may, it can reach three to four feet and contribute a fair amount of organic matter. Unless plowed under while quite small, it can be difficult to break up the clumps of winter rye, making it difficult to seed crops. (http://extension.umass.edu/vegetable/articles/soil-basics-part-iii) TANAMAN PENUTUP TANAH

8 Soil fertility and fertilisers The use of animal manure and compost contributes to retaining the level of organic matter in the soil. Chemical fertiliser can be needed to quickly supply a crop with required nutrients. In contrast to organic fertilisers, chemical fertilisers help the plants immediately; organic manures first have to be broken down into nutrients before they can be utilised by the plants. This means that organic material only has an effect in the long term, while chemical fertilisers contribute immediately (within a few days to weeks) to soil fertility. However, chemical fertilisers are depleted by the end of the season or seasons, while organic matter continues to enhance soil fertility as well as the soil structure. Moreover, the presence of organic material ensures that the chemical fertiliser is more efficiently utilised by the crop because it prevents the fertiliser from being leached. Sumber: ….. Diunduh 15/3/2012 SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, Pada tanah-tanah yang miskin bahan organik, aplikasi pupuk kimia buatan harus dibarengi dengan aplikasi bahan organik secukupnya

9 KESUBURAN TANAH DAN BUDIDAYA TANAMAN After an introduction about crop husbandry, organic matter, burning and the local conditions the crop husbandry systems are described in more detail: 1. mulching is a method, in which a layer fresh organic matter is placed on top of the soil; 2.green manuring consists in ploughing under fresh green material; 3.intercropping means growing two or more crops together on the same field; 4.during green fallow periods, species are sown or stimulated that have better qualities then the species that would grow spontaneously in the fallow period; 5.agroforestry comprises all forms of land use in which woody species (trees and shrubs) are grown in combination with other crops. Sumber: journeytoforever.org/farm_library/AD2.pdf….. Diunduh 15/3/2012 Intercropping is the practice of growing two or more crops in proximity. The most common goal of intercropping is to produce a greater yield on a given piece of land by making use of resources that would otherwise not be utilized by a single crop. Careful planning is required, taking into account the soil, climate, crops, and varieties. It is particularly important not to have crops competing with each other for physical space, nutrients, water, or sunlight. Examples of intercropping strategies are planting a deep-rooted crop with a shallow-rooted crop, or planting a tall crop with a shorter crop that requires partial shade. (http://en.wikipedia.org/wiki/Intercropping) INTERCROPPING

10 CROP HUSBANDRY SYSTEM Husbandry means managing resources or caring for animals and crops: 1.Thrifty management of a household is an example of husbandry. 2.The practice of managing a farm, growing crops and breeding animals is an example of husbandry. (sumber; (Husbandry) farming: the practice of cultivating the land or raising stock (sumber: ) Sumber: lada.virtualcentre.org/.../download.asp?pub….. Diunduh 18/3/2012 The concept of husbandry, signifying understanding, management and improvement, is widely understood when applied to crops and animals. It is equally applicable to land. Thus, land husbandry can be defined as “the care and management of the land for productive purposes; only through sound land husbandry can the land's productive potential be sustained and enhanced” LAND HUSBANDRY

11 Better Land Husbandry Components The intrinsic components to Better Land Husbandry (BLH): 1.Promotion of an integrated and synergistic resource management approach embracing locally appropriate combinations of the following technical options: Sumber: lada.virtualcentre.org/.../download.asp?pub….. Diunduh 18/3/2012 build-up of soil organic matter and related biological activity to optimum sustainable levels (for improved moisture and nutrient supply and soil structure) through the use of compost, farmyard manure, green manures, surface mulch, enriched fallows, agroforestry, cover crops and/or better crop residue management; integrated plant nutrition management with locally appropriate, and cost effective, combinations of organic/inorganic and on/off-farm sources of plant nutrients (e.g. organic manures, crop residues, rhizobial N-fixation, transfer of nutrients released by weathering in the deeper soil layers to the surface via tree roots and leaf litter, rock phosphate, lime and chemical fertiliser); better crop management, improved seeds of appropriate varieties, improved crop establishment at the beginning of the rains (to increase protective ground cover, thereby reducing water loss and soil erosion), weed management and integrated pest management; better rainwater management to increase infiltration and reduce runoff so as to improve soil moisture conditions within the rooting zone, thereby lessening the risk of moisture stress during dry spells, while reducing erosion; improvement of soil rooting depth and permeability through breaking of a cultivation- induced compacted soil layer (hoe/plough pan) through conservation tillage practices by means of tractor-drawn subsoilers, ox-drawn chisel ploughs, and hand-hoe planting pits/ double dug beds; and/or interplanting of deep rooted perennial crops/trees & shrubs); and reclamation, where appropriate (i.e. if technically feasible and cost effective), of arable land that has been severely degraded by such processes as gullying, loss of topsoil from sheet erosion, soil compaction, acidification and/or salinisation.. B.L.H.

12 PENN STATE EXTENSION. College of Agricultural Sciences AGRONOMY GUIDE. CROP AND SOIL MANAGEMENT. Section II. Soil Fertility Management The goal of soil fertility management is to create soil chemical conditions that encourage plant growth and supply required nutrients in the amounts and at the times they are most needed. Liming materials and plant nutrients may be added to the soil in many forms and can be done so in a way that maximizes the economic benefits of nutrients while minimizing any environmental impact. The ways in which crops respond to these applications often are different because some soils have inherent physical limitations to plant growth. Soil testing is the best guide to soil fertility. Plant tissue analysis also may be helpful when used in conjunction with soil testing. Sumber: Diunduh 15/3/2012 Uji Tanah dan Tanaman

13 A set of soil fertility management practices that necessarily include the use of fertilizer, organic inputs, and improved germplasm, combined with knowledge on how to adapt these practices to local conditions, and aiming to maximize agronomic use efficiency of the applied nutrients and thus crop productivity. All inputs are managed, using sound agronomic principles. Sumber: Diunduh 15/3/2012 ISFM interventions have been developed for maize, sorghum, and cassava-based systems in the major impact zones. Yield increases were over 100%, even as soil fertility status improved. Activities are now directed towards achieving the same successes with riceand banana-based systems. Conservation agricultural practices are also being developed.

14 PENGELOLAAN KESUBURAN TANAH Goals of a Sustainable Soil Fertility Management Program 1. To sustain high crop productivity and crop quality in food and fiber production a) Crop productivity, crop quality, and the success of a given operation 2. To minimize risks to environmental quality and human health associated with agricultural production a)Important steps in minimizing human health risks, and on and off-farm impacts 1.Avoid the use of all synthetically compounded materials; balance inputs of organic matter and mineral inputs to avoid exceeding crop needs 2.Avoid creating nonpoint source pollution through surface runoff and leaching 3.Prevent soil erosion and sedimentation of waterways 4.Close nutrient cycles as much as possible within the field and farm 5.Close nutrient cycles at multiple scales: watershed, regional and national scales Sumber: Diunduh 15/3/2012

15 Components of a Sustainable Soil Fertility Management Program 1. Improve and maintain physical and biological properties of soil a) Sustainable agricultural practices used to improve and sustain soil physical and biological properties i.Maintaining or building soil organic matter (SOM) levels through inputs of compost and cover cropping ii.Properly timed tillage iii.Irrigation iv.Sound crop rotations, soil amending, and fertilizing techniques all serve to improve the quality of agricultural soils, which in turn affects soil quality and crop performance. Sumber: Diunduh 15/3/2012 Integrated plant nutrient components in the Nepalese farming system 10.htm

16 Components of a Sustainable Soil Fertility Management Program 2. Improve and maintain chemical properties of soil a) Benchmarks of optimal soil chemistry i.Balanced levels of available plant nutrients (see Unit 1.11, Reading and Interpreting Soil Test Reports) ii.Soil pH ~6.0–7.0 iii.Low salinity levels b) Sustainable agricultural practices used to develop and maintain optimal soil chemical properties i.Provide a balanced nutrient supply for the crop ii.Conduct soil sampling and periodic monitoring iii.Conduct plant tissue testing iv.Time seasonal nutrient release from organic amendments to correspond with crop requirements: (a) The quality of the organic matter input; and (b) Environmental factors such as soil temperature and moisture v.Avoid leaving fields bare to avoid wind and water erosion and nutrient leaching vi.Manage irrigation carefully to avoid runoff, erosion, and leaching of soluble nutrients vii.Supply major nutrients primarily through organic matter and mineral soil amendments viii.Allow sufficient time for fresh residue to break down before planting crops ix.Use in-season supplemental fertilizers when necessary Sumber: Diunduh 15/3/2012 facts-31a

17 3. Minimize disease/pest susceptibility a) Sustainable agriculture practices used to minimize disease/pest susceptibility in organic farming systems 1.Maintain soil nutrient levels and soil pH within optimal range 2.Build and maintain soil organic matter to promote desirable soil physical 3.properties and supply essential plant nutrients 4.Maintain soil moisture within optimal ranges for plant growth and the avoidance of compaction and erosion 5.Design appropriate rotations to break pest cycles 6.Plant polycultures 7.Use appropriate preventative and active biocontrol practices Components of a Sustainable Soil Fertility Management Program Sumber: Diunduh 15/3/2012 Polyculture is agriculture using multiple crops in the same space, in imitation of the diversity of natural ecosystems, and avoiding large stands of single crops, or monoculture. It includes crop rotation, multi-cropping, intercropping, companion planting, beneficial weeds, and alley cropping. Polyculture, though it often requires more labor, has several advantages over monoculture: The diversity of crops avoids the susceptibility of monocultures to disease. For example, a study in China reported in Nature showed that planting several varieties of rice in the same field increased yields by 89%, largely because of a dramatic (94%) decrease in the incidence of disease, which made pesticides redundant (Nature 406, , 17 augt. 2000). The greater variety of crops provides habitat for more species, increasing local biodiversity. This is one example of reconciliation ecology, or accommodating biodiversity within human landscapes. It is also a function of a biological pest control program. (http://en.wikipedia.org/wiki/Polyculture)

18 Soil Fertility and Soil Quality in Sustainable Farming Systems KESUBURAN TANAH DAN KUALITAS TANAH a)Kualitas Tanah b)Indikator Kualitas Tanah 1.Ketersediaan hara 2.Ketersediaan air 3.Promotes good root growth and maintains good habitat for soil organisms 4.Mencegah degradasi 5.Maintains good soil structure to provide adequate aeration and tilth 6.Good soil structure allows for rapid water infiltration 7.pH moderat (6.0–7.5) 8.Tingkat salinitas rendah 9.Low levels of potentially toxic elements 10.Kesuburan tanah berimbang. c) Soil fertility: The capacity of a soil to provide nutrients required by plants for growth; one component of soil quality 2. Soil fertility, plant health, and the resistance and resilience of crop plants to pest and pathogens Sumber: Diunduh 15/3/2012 Concept of Nutrient Availability Soil is a living medium consisting of physical part - called as soil particles, chemical part - consisting of various compounds as well as biological part - consisting of various microbes, vertebrates, invertebrates inhabiting in soil. Unless all these components are kept in harmony, the crop plants would suffer by poor nutrient availability. Nutrients are made available to crop roots through the living media of soil mainly by processes called as 1.Mass flow 2.Cation exchange and anion exchange 3.Diffusion

19 PENGELOLAAN KESUBURAN TANAH PENGOLAHAN TANAH DALAM PERTANIAN BERKELANJUTAN 1. Services provided by tillage a) Prepares the ground for seedlings and transplants b)Provides a range of residue incorporation options c)Enables the incorporation of amendments d)Improves soil aeration, and breaks up soil clods to form good seed and root beds e)Improves water infiltration f)Increases rate of microbial activity and mineralization g)Deep tillage can break through compacted layers 2. Disadvantages of tillage a)Accelerates the rate and extent of long-term declines in soil organic matter b)May increase sub-soil compaction c)High energy and labor costs d)Loss of soil organic matter (SOM) from excessive tillage can lead to crusting of bare soils 3. Advantages of reduced and no-tillage systems a)Residue cover protects the soil from wind and water erosion b)Allows for greater moisture retention in rain-fed systems c)These systems build SOM over a period of years, and reach a higher “steady state” level than tilled systems in the same environment d)Reduced tillage in agricultural soils creates a greater carbon sink 4. Limitations of reduced and no-till agriculture systems a)Residue cover lowers soil temperature, which delays seed germination and slows seedling growth and may place growers at an economic disadvantage b)Weed control is very difficult without use of herbicides c)Requires specialized equipment to plant through thick layer of residue d)Increased leaching of nutrients and herbicides into the groundwater has been shown in some Sumber: Diunduh 15/3/2012

20 Cover Crops dalam Pertanian Berkelanjutan 1. Services provided by cover crops a) Cover crops increase nutrient availability i.The role of legume cover crops in biological N fixation and nutrient budgeting ii.Nutrients are released into the soil solution as the cover crop residues are broken down iii.Cover crops can stimulate microbial activity and increase the breakdown of existing SOM iv.Deep-rooted cover crops are able to recycle nutrients acquired from deeper in the soil profile v.Grass/cereal cover crops may reduce nutrient losses by capturing mobile nutrients (e.g., nitrate) 2. Influences on the nutrient release from cover crops a) Temperature and moisture conditions b) Placement of the residue i.Residue on soil surface: Will decompose more slowly due to drying ii.Incorporation into the top 6–8 inches of the soil: Will decompose most rapidly due to high oxygen levels and the presence of large populations of decomposing organisms iii.Below 6–8 inches: Will decompose more slowly due to lower oxygen levels, fewer decomposers c) Composition/“quality” of the cover crop residue i.The C to N ratio of the cover crop residue and N mineralization: (a) C/N ratios around 22:1 or less = net mineralization of N; (b) C/N ratios above 22:1 = net immobilization of N ii.Optimum stage of development to incorporate cover crops = 75%–100% of full bloom iii.The presence of lignins and tannins in cover crop residue slows decomposition PENGELOLAAN KESUBURAN TANAH Sumber: Diunduh 15/3/2012

21 Cover Crops dalam Pertanian Berkelanjutan 3. The timing of nutrient release, crop demand, and the fate of essential plant nutrients a)Managing the timing of nutrient release from cover crops to coincide with crop demand b)Leaching: Nutrients (N) can become vulnerable to loss if timing is mismatched c)Nutrient deficiencies: If timing is mismatched, nutrient deficiencies (N) may then result 4. Some effects of cover crops on agricultural soils a)Improvements to soil physical properties: Carbon and nutrient cycling through the use of cover crops b)The influence of cover crops on disease and pest severity i.Rye, triticale, forage rapeseeds, mustards, and oil seed radish are known to suppress certain plant parasitic nematodes and soil borne diseases ii.Many legumes can actually increase pest populations c) Weed-suppressive effects of cover crops i. Competition for light/smothering ii. Allelopathy 5. Importance of gathering regional cover crop information PENGELOLAAN KESUBURAN TANAH Sumber: Diunduh 15/3/2012 A cover crop is a type of plant grown to suppress weeds, help build and improve soil, and control diseases and pests. Cover crops are also called "green manure" and "living mulches." They're called "green manure" because they provide nutrients to the soil much like manure does. And as "living mulches," cover crops prevent soil erosion. Once grown, cover crops are usually mowed and then tilled into the soil.

22 KOMPOS DAN PUPUK KANDANG 1. Composts a) How much compost to apply annually b) The nutrient contribution of a manure-based compost: ~1N-1P-1K, i.e., balanced contribution of N-P-K. As nutrient levels in compost vary, it is recommended that you check with supplier or have a compost nutrient assessment done to confirm nutrient levels and proportions. c) Application timing: Nutrient release should ideally coincide with crop demand i.Depending on compost quality, may be an inefficient source of N in short term ii.Release of N may last 6 weeks–several months following incorporation, depending on compost quality and environmental conditions iii.Need to incorporate into root zone if applying mid season as side dress d) Compost quality indicators i.C:N ratio ii.CO2 levels iii.Ammonia levels iv.Smell v.Color vi.Texture/feel vii.Temperature e) Ease and economics of use f) Labor and/or equipment requirements for on-farm production of compost. g) National Organic Program standards for on-farm compost production h) Transportation issues: (i)Local/regional availability and costs; (ii)Variability in quality Sumber: Diunduh 15/3/2012 PENGELOLAAN KESUBURAN TANAH

23 Sumber: Diunduh 15/3/2012 PENGELOLAAN KESUBURAN TANAH a)The use of fresh and undecomposed manure in agricultural systems: Cropping in soils with fresh and/or undecomposed manures may result in nitrogen “burns” (due to high ammonium levels) and nitrate depression/net immobilization, respectively b)Restrictions on the use of manure under National Organic Standards c)Variations in the nutrient profiles of animal manures: The nutrient profile of fresh manures range from approximately (horse manure) to (poultry manure). d)Handling and storage of animal manures for the conservation of nutrients: Fresh animal manures should be temporarily stored and protected from sun and rain by covering with tarps e)Food safety issue: NOP guidelines designed to prevent contamination by E. coli and other disease-causing organisms PUPUK KANDANG Effect of Manure application on carbon budgets in ecosystems /slides/03/32.html

24 Soil Amendments and Supplemental Fertilizers 1. Organic amendments a) OMRI/NOP-certified materials in certified organic farming systems b) Nutrient budgeting 2. Supplemental fertilizers: When used 3. Soil fertility management and nutrient budgets: Balancing nutrient inputs with nutrient outputs each year a)Inputs > outputs = accumulation. Potential risk of excess nutrients creating nonpoint source pollution through leaching and run off, and enhancing disease and pest incidence. b)Inputs < outputs = soil depletion. Potential risk of plant nutrient deficiencies and stress, reduced yield, and increased susceptibility to pest and pathogens. c)Goal: Balance inputs and outputs once you have achieved desired/optimal nutrient levels in the soil. Example of inputs factored into budget for nitrogen i.Inputs = imported fertilizers and amendments + atmospheric deposition + N fixation through cover crops ii.Outputs = N exported in crop harvest + N lost through leaching, erosion, and denitrification iii.Calculating nutrient budgets: See Unit 1.11, Reading and Interpreting Soil Test Reports 4. Application of nutrient budgets in assessing the health of larger-scale units: Watersheds, regions.. Example of accumulation and depletion, e.g., the impact of high densities of confinement animal production facilities. Sumber: Diunduh 15/3/2012 PENGELOLAAN KESUBURAN TANAH

25 PERGILIRAN TANAMAN 1. Crop rotation 2. Rotation considerations a) Try to avoid rotation of crop species that share similar pests and diseases. Intersperse with different crops to break pest and disease cycles. Example: Solanaceae rotation b) Rotation of crops to maximize use of nutrient inputs and distribute nutrient demand placed on the soil. Examples of multi-year crop rotations (Coleman 1995) c) Fallow periods and perennial cover crop rotations Sumber: Diunduh 15/3/2012 PENGELOLAAN KESUBURAN TANAH Pola pergiliran tanaman sayuran dalam periode lima tahun ments/crop_rotation/

26 DINAMIKA HARA TANAH Mempertahankan jumlah optimum unsur hara hanya dapat terlaksana dengan menciptakan keseimbangan yang baik antara penambahan dan kehilangannya Benefits of Organic Matter Increases soil CEC Stabilizes nutrients Builds soil friability and tilth Reduces soil splash Carbon Sequestration C cycling in agroecosystems has a significant impact at the global scale because agriculture occupies approximately 11% of the land surface area of the earth. Benefits of Organic Matter Reduces compaction and bulk density Provides a food source for microorganisms Increases activities of earthworms and other soil critters Carbon sequestration is the capture of carbon dioxide (CO 2 ) and may refer specifically to: 1."The process of removing carbon from the atmosphere and depositing it in a reservoir.“ When carried out deliberately, this may also be referred to as carbon dioxide removal, which is a form of geoengineering.“ 2.The process of carbon capture and storage, where carbon dioxide is removed from flue gases, such as on power stations, before being stored in underground reservoirs. 3.Natural biogeochemical cycling of carbon between the atmosphere and reservoirs, such as by chemical weathering of rocks. (http://en.wikipedia.org/wiki/Carbon_sequestration)

27 PENTINGNYA PUPUK DAN PEMUPUKAN Balanced nutrition is important in obtaining maximum yields. The most usual limitations concern nitrogen, phosphorus and potassium, followed by sulphur. Sumber: ….. Diunduh 17/3/2012 Fertilizer is any organic or inorganic material of natural or synthetic origin (other than liming materials) that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use. They are essential for high-yield harvest. (http://en.wikipedia.org/wiki/Fertilizer)

28 KETERSEDIAAN UNSUR HARA DAN pH Sumber: Diunduh 15/3/2012 Nutrient availability and soil pH Some generalizations can be made regarding the availability of nutrients to plants in relation to soil pH. Deficiencies of zinc, manganese, and iron are more common on alkalines soils while deficiencies of molybdenum, calcium, and magnesium occur more commonly on acid soils. For other nutrients such as potassium and sulfur, there is little association between soil pH and availability to plants. Toxicities of aluminum and manganesse occur almost exclusively on acid soils. (http://wheatdoctor.cimmyt.org/en/nutrient-problems/list/176?task=view) Chart of the Effect of Soil pH on Nutrient Availability

29 Cation Exchange Capacity – Everything You Want to Know and Much More James J. Camberato Clemson University, Crop and Soil Environmental Science RINGKASAN Cation exchange capacity (CEC) is the amount of negative charge in soil that is available to bind positively charged ions (cations). Essential plant nutrients, K+, Ca2+, Mg2+, and NH4 + and detrimental elements, Na+, H+, and Al+3 are cations. Cation exchange capacity buffers fluctuations in nutrient availability and soil pH. Clay and organic matter are the main sources of CEC. The CEC of most native soils in the Carolinas and sand-based sports fields is low because they are low in clay and organic matter. What little CEC exists in these soils is pH dependent, thus it is beneficial to maintain soil pH near 6.5 for optimum levels. Adding calcined clay, diatomaceous earth, or zeolite/clinoptilolite increases CEC, but the benefits of adding these materials in lieu of peat or organic matter maintenance are not well established. Cation exchange capacity is estimated and reported by most soil testing laboratories. Estimates are reasonably accurate unless the soil has been heavily fertilized or amended just prior to sampling or an acid extractant was used on a soil containing precipitated calcium carbonate. Base saturation, the quantity of CEC occupied by one or more of the basic cations, is useful for managing detrimental levels of soil Na+ and Mg2+ availability. Sumber: ….. Diunduh 15/3/2012

30 Organic matter, nutrient contents and cation exchange capacity in fine fractions from semiarid calcareous soils F. Caravaca ), A. Lax, J. Albaladejo. Geoderma –176 ABSTRACT Soil erosion, which is a widespread problem in semiarid areas, may lead to a decline in soil productivity since the finest and most fertile soil particles are those which are generally removed. Our objective was to determine the distribution of soil organic matter, phosphorus, potassium and cation exchange capacity within the fine fractions -2 mm and 2–20 mm. of the soil. Samples were taken from the top 20 cm of 14 cultivated soils and six forest soils. The organo-mineral size fractions from soil samples were isolated without chemical pretreatment by ultrasonic dispersion in water followed by sedimentation–syphonation. The distribution of organic matter within size fractions varied with land use. The cultivated soils had a greater percentage on average, about 30%. of total soil C in the -2 mm fraction than the soils under natural vegetation on average, about 18%., in which the total soil C was associated with the 2–20 mm fraction to a greater extent than in cultivated soils. The distribution of the soil N between the clay and fine silt size fractions followed a similar pattern to that shown by soil C. The C/N ratio became smaller as particle size decreased. The higher C/N ratio obtained for the 2–20 mm fraction for both forest and cultivated soils suggests the presence of less decomposed organic matter, while the organic matter associated with the -2 mm fraction can be considered to be more humified. The cation exchange capacity of whole soil and organo-mineral fractions were closely correlated with their respective C contents. The clay-size fraction had the highest CEC, which was related to its mineralogical composition. The data confirm that the proportion of soil organic matter depends on the stabilizing capacity of the different size fractions, both the clay and fine silt size fractions playing an important role in semiarid soils. To the detriment of the soil’s organic matter content these fractions are easily eroded in soils under arid and semiarid conditions, which may render them unsuitable for agricultural purposes.. Sumber: Diunduh 15/3/2012

31 POKOK-POKOK PENGELOLAAN KESUBURAN TANAH. 1.Suplai nitrogen dari: 2.Sisa TanamanTanaman biasa Pupuk kandangTanaman legume Hujan & irigasiPupuk hijau Pupuk nitrogenKompos 2. Penambahan bahan organik melalui: Sisa tanaman legume dan non legume Pupuk kandang Pupuk hijau 4. Penambahan fosfat: Pupuk superfosfat, atau Pupuk lainnya 3. Penambahan kapur bila diperlukan Batu kapur kalsit atau dolomit yg biasa dilakukan 7. Penambahan unsur mikro: Sebagai garam terpisah atau campuran 5. Penambahan kalium tersedia: Pupuk kandang Sisa tanaman Pupuk Kalium 6. Kekurangan belerang diatasi dg: Belerang, gipsum, superfosfat, Amonium sulfat, Senyawa belerangdalam air hujan

32 THE FATE OF PHOSPHATE FERTILISERS IN SOIL I.S. Cornforth (Department of Soil Science, Lincoln University) Phosphorus participates in many of the reactions that keep plants and animals alive, and is thus essential for all living organisms. Phosphorous is found in two different forms in soil: inorganic and organic. Inorganic phosphorus The main inorganic forms of phosphorus in soil are H2PO4- and HPO42-. This is the form in which phsophorus is used by plants. However, these ions can also absorb onto the surface (or adsorb into) solid matter in the soil. This phosphorus is then unavailable to plants. Organic phosphorus Between 50 and 80% of phosphorus in soil is organic phosphorus. This comes from the breakdown of dead plants etc., as phosphorus is found in cell membranes and DNA in living organisms. Phosphorus is thus naturally available in the soil. However, there isn't usually enough available for plants to grow well. Phosphorus levels are reduced by animals eating the plants then dying elsewhere so that the phosphorus is removed, and also by phosphorus being adsorbed into soil particles or washed away by excess rain. For this reason phosphate fertilisers are widely used. The ways in which this influences phosphate cycling in the soil are discussed in more detail in the following article. Sumber: Diunduh 15/3/2012 As a particle of fertilizer comes in contact with the soil, moisture from the soil will begin dissolving the particle. Dissolving of the fertilizer increases the soluble phosphate in the soil solution around the particle and allows the dissolved phosphate to move a short distance away from the fertilizer particle. Movement is slow but may be increased by rainfall or irrigation water flowing through the soil. As phosphate ions in solution slowly migrate away from the fertilizer particle, most of the phosphate will react with the minerals within the soil. Phosphate ions generally react by adsorbing to soil particles or by combining with elements in the soil such as calcium (Ca), magnesium (Mg), aluminum (Al), and iron (Fe), and forming compounds that are solids. The adsorbed phosphate and the newly formed solids are relatively available to meet crop needs. (http://www.extension.umn.edu/distribution/cropsystems/DC6795.html) The availability of phosphorus is affected by soil pH.

33 Examples of phosphate adsorption mechanisms Sumber: Diunduh 15/3/2012 THE FATE OF PHOSPHATE FERTILISERS IN SOIL I.S. Cornforth (Department of Soil Science, Lincoln University)

34 The absorption of adsorbed P into soil minerals (a) and the subsequent occlusion of adsorbed P (b) Sumber: Diunduh 15/3/2012 THE FATE OF PHOSPHATE FERTILISERS IN SOIL I.S. Cornforth (Department of Soil Science, Lincoln University)

35 THE DYNAMICS OF POTASSIUM (K) IN REPRESENTATIVE SOIL SERIES OF GHANA D. O. Yawson, P. K. Kwakye, F. A. Armah and K.A. Frimpong. ARPN Journal of Agricultural and Biological Science VOL. 6, NO. 1, JANUARY 2011 ABSTRACT The immediate supply of K by soils to growing plants derives mainly from the K that is labile whereas the long term K nutrition of plants depends on the non-labile K. The dynamic relationship between these forms of K constitutes the dynamics of K in soils. Most Ghanaian farmers grow root and tuberous crops which have high K requirements. Knowledge of K dynamics in soils is therefore essential for K management to sustain crop production and management of agro-ecological environments in Ghana. Quantity-Intensity isotherms provide a better overview of K dynamics in soils. Therefore, Quantity/Intensity (Q/I) curves were used in this study to evaluate the dynamics of K in ten soil series representing the major agro-ecological zones of Ghana. K dynamics in the soils were found to be influenced by some soil properties. Significant correlations were found between soil properties and Q/I parameters; and among equilibrium solution parameters and Q/I parameters. There was no significant variation among the mean quantity (±ΔK) values of the soils. The savannah soils had higher non-specific K, K-potential, and potential buffering capacity (PBC K ) than the forest soils; and the Akuse series had the highest values for these parameters. However, the forest soils had higher K-intensity. Therefore, the forest soils will require frequent and split K applications since they have lower capacity to maintain long-term supply of K. However, the savannah soils will require less frequent but higher K fertilization to satisfy the exchangeable pool and immediate plant nutrition requirement Sumber: Diunduh 15/3/2012

36 SOIL FACTORS AFFECTING MAGNESIUM AVAILABILITY IN PLANT-ANIMAL SYSTEMS: A REVIEW I H. F. Mayland and S. R. Wilkinson. J. Anita Sei : ABSTRACT Soils provide the support, water and most of the nutrient elements, including Mg, needed for plant growth. Magnesium uptake by plants depends largely on the amount, concentration and activity of Mg in the soil solution and the capacity of the soil to replenish Mg in the soil solution. The availability of Mg depends on the activity or proportion of Mg relative to soluble and exchangeable amounts of K, Ca, Na, AI and Mn. In humid regions, Mg losses from leaching are often greatest from agroecosystems receiving heavy N fertilization. Cool- season grasses produce nearly maximum growth at herbage concentrations of 1 to 1.5 g Mg/kg, 25 g K/kg and 30 g N/kg of dry matter. At these concentrations of N and K, herbage should contain about 2.5 g Mg/kg to avoid inducing hypomagnesemic grass tetany in ruminants. To increase herbage Mg concentration to this level often requires, except on sandy soils, an uneconomically large addition of Mg fertilizer. Adjusting soil conditions to produce grasses with a low-tetany potential may not always be possible physically. The risk of tetany can be reduced by a judicious program of well-timed N, K and Mg fertilizer applications. However, direct Mg supplementation of grazing ruminants is considered more cost-effective than is Mg fertilization to prevent grass tetany. Sumber: ….. Diunduh 15/3/2012

37 Effects of Potassium Fertilization on Soil Potassium Distribution and Balance in Pistachio Orchards David Qiupeng Zeng, Patrick H. Brown, and Brent A. Holtz Better Crops/Vol. 83 (1999, No. 4) Potassium distribution in the soil profile is characterized by decreasing soil K content with depth. Potassium fertilization significantly increased soil K content throughout the 0 to 30 inch soil profile, even though the movement of surface-applied K in the soil profile was slow. More K was accumulated in the fruit and leaves in pistachio trees treated with K. Soil K balance data showed that without K fertilization, soil available K was rapidly depleted. To accurately diagnose soil K deficiency and to determine K fertilization requirements in pistachio, it is important to examine K status in the irrigated soil profile. Sumber: Diunduh 15/3/2012 Fertilizer and Management Practices Increased use of nitrogen (N) and other limiting nutrients. When adequate K is available, addition of N and/or phosphorus (P) greatly increases K uptake, as yields are increased. Usually the uptake of K by crops closely parallels N uptake and may be greater. So, as limiting nutrients are added, the demands on soil K increase. Applications of K in fertilizers, manures or crop residues. The major way to increase K availability is to apply adequate amounts. Potassium is readily available from all these sources, provided they are located where roots can absorb the K. Placement of K. Broadcast plow-down applications of K are more available than surface applied disked-in K. Row K at moderate rates and soil test levels is usually twice as available to corn as similar amounts broadcast. Deep placement or drip irrigation helps move K down. Gypsum applied with K also helps move K down in very fine textured soils. Conservation tillage limits availability of surface applied K. Soil K levels should be built to high levels before shifting to minimum or conservation tillage. This improves K distribution within the plow layer. In many fine textured soils, surface applied K moves very little in the soil and has low availability, particularly under dryland conditions. Drainage increases K availability. Draining soils of excess moisture helps many soils warm up and improves the soil aeration. This improves the availability of soil K. Weed and insect control. Controlling weeds and insects reduces competition for moisture and nutrients, so that the crop being produced has relatively more K available. (http://www.ipni.net/ppiweb/bcrops.nsf/$webindex/726438DEC39EDF F000677EB8/$file/98-3p14.pdf)

38 Effects of Potassium Fertilization on Soil Potassium Distribution and Balance in Pistachio Orchards David Qiupeng Zeng, Patrick H. Brown, and Brent A. Holtz Better Crops/Vol. 83 (1999, No. 4) Sumber: Diunduh 15/3/2012 Potassium distribution in the soil profile after three years of K fertilization at various rates in the Madera orchard. Each value is the average of five repli cates ± standard error.

39 MENGATASI KEKURANGAN NITROGEN Penambahan & Kehilangan N- tersedia N-tersedia dlm tanah Atmosfer Pengikatan Nitrogen Pupuk Buatan Simbiotik Non-Simbiotik Sisa tanaman Pupuk Kandang Bahan Organik Panen Tanaman Hilang Pencucian Hilang Erosi The term “Agronomic Optimum N Rate” or AONR defines the N rate that will produce maximum grain yield, regardless of cost. The term “Economic Optimum N Rate” or EONR defines the N rate that will result in the maximum dollar return to N. The EONR is usually less than the AONR, will usually decrease as N prices increase, will usually increase as grain prices increase, or may remain the same if the ratio between nitrogen cost and grain price (N:G) remains the same. (http://www.agry.purdue.edu/Ext/corn/news/timeless/nitrogenmgmt.pd f)

40 The fate of nitrogen from legume and fertilizer sources in soils successively cropped with wheat under field conditions J.N. Ladd, M. Amato Soil Biology and Biochemistry. Volume 18, Issue 4, 1986, Pages 417–425 Abstract Using 15 N-labelled legume material (Medicago littoralis) and fertilizers (urea, (NH 4 ) 2 SO 4, KNO 3 ), a direct comparison has been made of the fate of nitrogen from these sources and their residues, in soils sown with two successive wheat crops. The availability of N from each source to both crops is discussed in terms of the release, movement and immobilization of N in the soil profiles. For fertilizer 15 N, uptake by crops, distribution as inorganic 15 N in soil profiles, total recovery and percentage recovery in organic residues in soil were not significantly influenced by the form of fertilizer applied. For both legume and fertilizer 15 N, uptake by both crops was directly related to input; and uptake by the second crop was directly related to the amounts of 15 N residual in soil after the first crop. About 17% of applied legume N was taken up by the tops of the first wheat crop, and, at the time of sowing of the second crop, about 62% remained as organic residues; total recovery in crop and soil averaged 84%. By contrast, about 46% of applied fertilizer N was taken up by crop 1, and at sowing in the following year 29% was present as organic residues, and total recovery in soil plus crop averaged 80% The availabilities of N from both legume and fertilizer residues to a second wheat crop declined markedly but continued to differ significantly (P < 0.01) from each other. Expressed as percentages of total residual 15 N present in soils at sowing, the second crop took up about 6% of legume-derived N and about 9% of fertilizer-derived N. Fertilizer N directly contributed 5% and 0.5% respectively of the N of first and second wheat crops, per 10kg of fertilizer N applied ha −1. Under the same conditions, legume N directly contributed about 2% and 1% respectively of the N of successive crops, per 10 kg of legume N applied ha −1. The proportions of grain N derived from the applied sources were higher than those of straw N. For both legume and fertilizer 15 N, the amounts of inorganic 15 N present in soil profiles at sowing in successive years were directly related to 15 N inputs. A small but statistically-significant departure from linearity was observed for inorganic 15 N at sowing of crop 2 when related to total recoveries of 15 N in soils at that time; the higher the amount of 15 N recovered, the greater the proportion present as inorganic 15 N in the soil profile. The respective contributions of legume and fertilizer N to the total inorganic N pool in soil at sowing declined each year, but were similar to their contributions to the N of the following wheat crop. Concentrations of inorganic N and 15 N in soil profiles varied each year but their patterns of distribution in cropped soils were not influenced by the nature and amount of the initial amendments. The 15 N atom% enrichments of the inorganic N at sowing in the cropped soils were relatively uniform throughout the profile. Sumber: ….. Diunduh 15/3/2012.

41 Soil & Tillage Research 33 (1995) Traffic and residue management systems: effects on fate of fertilizer N in corn H.A. Torbert, D.W. Reeves. ABSTRACT Soil compaction has been recognized as a problem limiting crop production, especially in the Southern Coastal Plain of the USA. Development of tillage and residue management systems is needed to alleviate soil compaction problems in these soils. Fertilizer nitrogen (N) management is also an important factor in these management systems. In 1988, a study was initiated with a wide-frame (6.3 m) vehicle to determine the interactive effects of traffic, deep tillage, and surface residue management on the fate of fertilizer N applied to corn ( Zea mays L.) grown on a Norfork loamy sand (fine-loamy, siliceous, Thermic, Typic Kandiudults). Corn was planted into a winter cover crop of 'Tibbee' crimson clover ( Trifolium incarnatum L ). Treatments included: traffic (conventional equipment or no traffic): deep tillage (no deep tillage, annual in-row subsoiling, or one-time only complete disruption); residue management (no surface tillage or disk and field cultivation). The one-time only complete disruption was accomplished by subsoiling at a depth of 43 cm on 25 cm centers in spring In , fertilizer applications were made as 15 Ndepleted NH4NO3 to microplots inside each treatment plot. The 1990 and 1991 data are reported here. In 1990 an extreme drought resulted in an average grain yield of 1.8 Mg grain ha -1. whereas abundant rainfall in 1991 resulted in 9.4 Mg grain ha -1. Deep tillage Increased corn dry matter production in both years. In 1991, grain yields indicated that corn was susceptible to recompaction of soil owning to traffic when residues were incorporated with surface tillage. In the dry year, plant N uptake was increased 27% with deep tillage and decreased 10% with traffic. In the wet year, a surface tillage x deep tillage x traffic interaction was observed for total N uptake, fertilizer N uptake, and total fertilizer N recovery in the plant-soil system. When combined with traffic, plant N uptake was reduced with the highest intensity tillage treatment (135 kg N ha -1 ) because of rootrrestricting soil compaction. and with the lowest intensity tillage treatment (129 kg N ha -1 ) because of increased N losses. In these soils, leaving residues on the soil surface can reduce the detrimental effect of traffic on corn production, but if no surface tillage is performed, deep tillage is needed.

42 SOIL ORGANIC MATTER AS A FUNCTION OF NITROGEN FERTILIZATION IN CROP SUCCESSIONS Renato Yagi; Manoel Evaristo Ferreira; Mara Cristina Pessôa da Cruz; José Carlos Barbosa; Luiz Alberto Navarro de Araújo. Sci. Agric. (Piracicaba, Braz.), v.62, n.4, p , July/Aug ABSTRACT The interdependence between the C and N cycles is reflected by the levels of soil organic matter (SOM). SOM and organic C levels in water soluble (C-WS) humic acids (C-HA), fulvic acids (C-FA), and humin fractions (C-H) were evaluated through the classic chemical fractionation method in samples of a Rhodic Eutrudox from a randomized blocks experimental design, with split-split-plots using five nitrogen sidedressing levels for corn (0; 60; 120; 180; and 240 kg ha-1 N) as the main treatment, two crop sequences (corn-corn and soybean-corn) as the secondary treatment, and two sampling depths (0 to 0.2 and 0.2 to 0.4 m) as a sub-subtreatment. Nitrogen fertilization did not affect SOM levels, but favored the synthesis of substances in the C-HA fraction. There was a quadratic effect of N rates on the C-WS and C-FA levels in the corn-corn succession. The soybean-corn succession resulted in larger SOM and organic C levels in the C-H fraction. Sumber: Diunduh 15/3/2012 N in soil organic matter – How much is released? It is not uncommon for some to use a general rule of thumb of about 1 to 2% release of N in soil organic matter, during the spring through summer growing season each year. The release rate varies with soil texture or CEC, soil pH, soil microbial population, the prevailing temperature and moisture, as well as with any soil disturbance by tillage. The range of N released (mineralized) by soil microbes may be approximately 10 to 80 lb/A each growing season, or more. Obviously, more N is released during warm, moist conditions as opposed to those that are cool and dry. With such a broad range, it is no surprise that there have been many attempts to develop more reliable measures of “potentially available soil N”, and in some regions, soil N tests have met with some calibration and field validation success. Often, these “potentially available soil N” tests require sampling beyond the typical 0 to 6 in. depth, and may require sampling to 2 or 3 ft. deep. (Sumber: released-into-fields html ….. Diunduh 21/3/2012 )

43 MEMPERTAHANKAN BAHAN ORGANIK TANAH Carbon Inputs to Soil Crop residues Cover crops Compost, and Manures Carbon Substrate The majority of C enters the soil in the form of complex organic matter containing highly reduced, polymeric substances. During decomposition, energy is obtained from oxidation of the C-H bonds in the organic material. Soil Carbon Equilibrium Input primarily as plant products Output mediated by activity of decomposers It is common that from 40 to 60% of the C taken up by microorganisms is immediately released as CO2. Managing soil carbon Natural variations in SOM occur as a result of climate, organisms, parent material, time and relief. The greatest contemporary influence has been that of humans; for example, historical SOM in Australian agricultural soils may have been twice the present range that is typically from 1.6 to 4.6 per cent. It has long been encouraged that farmers adjust practices to maintain or increase the organic component in the soil—on one hand, practices that hasten oxidation of carbon, such as burning crop stubbles or over-cultivation are discouraged; on the other hand, incorporation of organic material, such as manuring has been encouraged. Increasing soil carbon is not a straightforward matter—it is made complex by the relative activity of soil biota, which can consume and release carbon and are made more active by the addition of nitrogen fertilizers. (http://en.wikipedia.org/wiki/Soil_carbon)

44 Soil Quality Technical Note No. 5 Managing Soil Organic Matter The Key to Air and Water Quality USDA Technical Note No. 5 October 2003 Praktek budidaya yang memperbaiki BOT: Diversifikasi pergiliran tanaman yang kaya biomasa Tanaman penutup tanah Olah tanah minimum Rotational grazing Organic matter dynamics change Increased surface residue forms a physical barrier to wind and water erosion. Higher residue rotations and cover crops contribute more organic matter and nutrients to the soil. Less soil disturbance means lower organic matter losses. Perubahan Sifat tanah Struktur tanah la[pisan permukaan menjadi lebih stabil dan lebih tahan terhadap penghancuran dan erosi. Infiltrasi air meningkat dan runoff menurun kalau struktur tanah menjadi lebih baik. BOT mampu memegang air dan hara sebanyak kali lebih banyak dibandingkan dnegan mineral tanah. Mikroba tanah yang “bermanfaat” menjadi lebih banyak dan aktif dengan semakin beragamnya pergiliran tanaman dan BOT yang semakin banyak. Sumber: ….. Diunduh 15/3/2012

45 Oklahoma Cooperative Extension Fact Sheets are also available on our website at: Building Soil Organic Matter for a Sustainable Organic Crop Production Strategi untuk meningkatkan BOT The methods used for building SOM depend on several factors. One factor is the goal of the practice. Is the goal simply to supply nutrients or to supply both nutrients and build OM in the soil? This question refers to whether a producer should engage in supplying nutrients to make sure higher yield is achieved in the short-term or to consider both yield and conditioning the soil for optimum long-term production. Another factor that affects the strategy is the type of organic enterprise. A producer needs to answer whether they are interested in: A livestock-crop mixed organic production system Perennial or annual agronomic crops Fruits or vegetables A mixed cropping system It is also important to know the soil type and problems specific to that soil. What is the physical and chemical composition of the soil? For soils rich in nutrients, but difficult to cultivate due to drainage problems, for example, raising the SOM level is recommended. Some soils are low in available nutrients; the strategy should be to supply nutrients as well as build SOM. Similarly, the nature of existing soil problems, such as low or very high pH and salt problems, must be taken into consideration. There are two strategies to build and maintain SOM for organic or, for that matter, any agricultural production system: reduce SOM losses and add organic material. Sumber: … Diunduh 15/3/2012

46 APLIKASI BAHAN ORGANIK KE TANAH There are wide ranges of options that an organic producer can use to add OM to the soil. Organic materials are highly variable in mineralization pattern, nutrient content, and availability. That is why it is important to set a goal and develop a best management plan for a given field. Cover crops, green manure, residue and live mulch, animal waste, compost, uncomposted yard debris, and packaged organic fertilizers are some of the major materials for building SOM. If a producer is planning a certified organic enterprise, it is important to know the allowed and non-allowed organic materials and their sources by national and state organic program rules and regulations. Oklahoma Cooperative Extension Fact Sheets are also available on our website at: Building Soil Organic Matter for a Sustainable Organic Crop Production Sumber: … Diunduh 15/3/2012 Schematic illustration of the pools and fluxes included in MAGIC for use in simulating the dynamics of organic and inorganic nitrogen in soils (sumber: DIUNDUH 21/3/2012)

47 TANAMAN PENUTUP TANAH DAN PUPUK HIJAU A cover crop is defined as any crop that is planted in a field after or prior to harvest of the major crop to cover the field until the next main crop is planted. A green manure crop is the crop grown on a field and then turned under when still green before the main crop is sown largely to supply nutrients, but also to contribute to the addition of OM. Cover and green manure crops serve four purposes: add OM, supply nutrients, prevent erosion, and prevent leaching by scavenging plant nutrients such as NO3— which otherwise may be leached into ground water. The contribution of cover and green manure crops to build SOM depends on the C:N ratio of the crops. There are four types of cover or green manure crops. Oklahoma Cooperative Extension Fact Sheets are also available on our website at: Building Soil Organic Matter for a Sustainable Organic Crop Production Sumber: … Diunduh 15/3/2012 Schematic representation of the factors concerning in tree – cover crop system above- and belowground. The tree – cover crop system concerns many factors above- and belowground. These can have significant effects on major processes in agricultural ecosystems and positively influence the soil and environmental quality in a long-term (sumber: …… diunduh 21/3/2012)

48 Maintaining and Monitoring Soil Organic Matter Once an acceptable level of SOM (about 3.5 to 4.0 percent) is obtained, it is desirable to maintain it. As a rule of thumb returning about two to three tons of organic material per year per acre would maintain an acceptable SOM level. Indicators used to monitor the status of soil organic matter in organic production. Oklahoma Cooperative Extension Fact Sheets are also available on our website at: Building Soil Organic Matter for a Sustainable Organic Crop Production Sumber: … Diunduh 15/3/2012

49 Microbial biomass – a significant source for soil organic matter Matthias Kaestner and Anja Miltner Geophysical Research Abstracts Vol. 13, EGU , 2011 ABSTRACT The formation of soil organic matter (SOM) has long been a dominating topic in soil science because the amount and composition of SOM determines soil quality but the processes are still not yet really understood. However, proper management of soil organic matter (SOM) is needed for maintaining soil fertility and for mitigation of the global increase of the atmospheric CO2 concentration. It needs to be based on knowledge about the sources, the spatial organisation and the stabilisation processes of SOM. On the molecular level, the degraded plant-derived organic material in soil is considered to be self-assembled and arranged to macromolecular complexes. Both easily degradable and refractory compounds are stabilised in these aggregates. In addition, the so-called humic substances were regarded for a long time as a novel category of cross-linked organic materials. Recently, microbial biomass residues have been identified as a significant source for SOM. We incubated 13C-labelled bacterial cells in an agricultural soil and traced the fate of the 13C label of bacterial biomass in soil by isotopic analysis. In this study, we summarise the mass balance data and visualise the microbial biomass and its residues by scanning electron microscopy (SEM). Our results indicate that a high percentage of the biomass-derived carbon remains in soil, mainly in the non-living part of SOM after extended incubation. The SEM micrographs only rarely show intact cells. Instead, organic patchy fragments of nm size are abundant. These fragments are associated with all stages of cell envelope decay and fragmentation. Similar fragments develop on initially clean and sterile in situ microcosms during exposure in groundwater providing evidence for their microbial origin. Microbial cell envelope fragments thus contribute significantly to SOM formation. The results provide a simple explanation for the development of the small, nano-scale patchy organic materials observed in soil electron micrographs. They suggest that microstructures of microbial cells and of small plant debris provide the molecular architecture of SOM adsorbed to particle surfaces. This origin and macromolecular architecture of SOM is consistent with most observations on SOM, e.g. the abundance of microbial-derived biomarkers, the low C/N ratio, the water repellency and the stabilisation of microbial biomass. The specific molecular architecture determines carbon mineralisation and balances as well as the fate of pesticides and environmental contaminants. Sumber: ….. Diunduh 17/3/2012

50 . Effect of cover crop management on soil organic matter Guangwei Ding, Xiaobing Liu, Stephen Herbert, Jeffrey Novak, Dula Amarasiriwardena, Baoshan Xing. Geoderma. Volume 130, Issues 3–4, February 2006, Pages 229–239. Abstract Characterization of soil organic matter (SOM) is important for determining the overall quality of soils, and cover crop system may change SOM characteristics. The purpose of this study was to examine the effect of cover crops on the chemical and structural composition of SOM. We isolated humic substances (HS) from soils with the following cover crop treatments: (a) vetch (Vicia Villosa Roth.)/rye (Sesale cereale L.), (b) rye alone, and (c) check (no cover crops) that were treated with various nitrogen (N) fertilizer rates. CPMAS-TOSS (cross-polarization magic-angle-spinning and total sideband suppression) 13 C NMR results indicated that humic acids (HA) from soils under rye only were more aromatic and less aliphatic in character than the other two cover crop systems without fertilizer N treatment. Based on the DRIFT (diffuse reflectance Fourier transform infrared) spectra peak O/R ratios, the intensities of oxygen-containing functional groups to aliphatic and aromatic (referred to as recalcitrant) groups, the highest ratio was found in the HA from the vetch/rye system with fertilizer N. The lowest ratio occurred at the vetch/rye system without fertilizer N treatment. The O/R ratio of fulvic acids (FA) can be ranked as: vetch/rye without fertilizer>vetch/rye with fertilizer>no cover crop without fertilizer>rye alone (with or without fertilizer) soils. Both organic carbon (OC) and light fraction (LF) contents were higher in soils under cover crop treatments with and without fertilizer N than soils with no cover crop. These chemical and spectroscopic data show that cover crops had a profound influence on the SOM and LF characteristics. Sumber: ….. Diunduh 17/3/2012

51 PENTINGNYA Ca & Mg Liming Benefits reduces the possibility of Mn2+ and Al3+ toxicity; improves microbial activity; improves physical condition (better structure); improves symbiotic nitrogen fixation by legumes; improves palatability of forages; provides an inexpensive source for Ca2+ and Mg2+ when these nutrients are deficient at lower pH; improves nutrient availability (availability of P and Mo increases as pH increases at 6.0 – 7.0, however, other micronutrients availability increases as pH decreases). (http://soils.usda.gov/sqi/management/files/sq_atn_8.pdf) Penambahan dan kehilangan Ca dan Mg tersedia dalam tanah Sisa tanaman & Pupuk Kandang Pupuk Komersial Mineral Tanah KAPUR PANEN TANAMAN Hilang pencucian Hilang Erosi

52 Effects of Liming to Near-neutral pH on Vitis vinifera L. J. Wooldridge, P.J.E. Louw and W.J. Conradie. S. Afr. J. Enol. Vitic., Vol. 31, No. 1, 2010 ABSTRACT Wine grape vines are sensitive to soil pH and liming. The effects of pre-plant liming at rates sufficient to promote average soil pH levels (1M KCl) of 5.05 (unlimed, treatment L0), 5.64 (L1) and 6.56 (L2) in two wine grape (scion) varieties and four rootstocks five years after planting were investigated over six seasons in a factorial field trial at Stellenbosch. Yields tended to decrease in the sequence: L0 > L1 > L2, and were significantly (P = 0.05) lower in L2 than in L0. Conversely, cane masses increased progressively with lime application rate, with L1 exceeding L0 by 11.0% and L2 exceeding L1 by 13.0%. These increases were significant. Compared to L0, liming decreased the ratio of yield to cane mass by 13.6% in L1 and 28.8% in L2, but increased Ca:Mg ratios in the soil and petioles. Wine quality was significantly better from L0 than L2. Petiole N concentrations were above normal in all treatments. Suppressed yields and wine quality in the limed treatments were attributed to a lime-induced imbalance between vegetative and reproductive growth, possibly exacerbated by increased Ca:Mg ratios and excess nitrogen. Sumber: netrul%20pH.pdf ….. Diunduh 15/3/2012

53 Dolomite Lime’s Reaction Applied on the Surface of a Sandy Soil of the Northwest Paraná, Brazil Anderson R. Meda; Marcos A. Pavan; Marcelo E. Cassiolato and Mário Miyazawa. BRAZILIAN ARCHIVES OF BIOLOGY AND TECHNOLOGY. AN INTERNATIONAL JOURNAL. Vol.45, N. 2 : pp , June 2002 ABSTRACT Low Ca and Mg are serious limitations to crop production in sandy soils of the northwest Paraná, Brazil. Thus soil samples of an Oxisol collected in this region were packed into 30cm long columns. Dolomite lime (2.0, 0.84, 0.30, and < 0.30 mm screen) was added on soil surface, then leached with deionized water. Thereafter, the columns were dismantled and the soil cut into 5cm segments for chemical analysis. Dolomite lime increased pHCaCl2,, Kclexchangeable Ca and Mg and residual CO3 mostly in the top surface layers. Surface dolomite lime had no effect on pH, Ca, Mg, and CO3 in the leachate, independent on the lime particle size. These results indicated that surface dolomite lime application had no effect on subsoil composition and mostly of the calcium and magnesium carbonates are still unreacted on the soil surface. Sumber: ….. Diunduh 15/3/2012

54 Effect of ammonium fertilizer on NH 3 loss and Ca, Mg, ammonium and nitrate content in a calcareous soil solution L. B. Fenn and E. Wu. Biology and Fertility of Soils. Volume 5, Number 2, Abstract This study examined the effects of NH inf4 + fertilizers [(NH 4 ) 2 SO 4, (NH 4 ) 2 HPO 4, CO(NH 2 ) 2, NH 4 OH, and NH 4 NO 3 ] on NH 3 loss and the quantity of Ca + Mg, NH inf4 + and NO inf3 sup– in the solution of a calcareous soil (Harkey sicl, Typic Torrifluvent). Various NH 4 fertilizers applied at a depth of 5 cm in the soil produced differing NH 3 loss characteristics. Applying (NH 4 ) 2 SO 4 (AS) resulted in high volatile NH 3 losses as compared with NH 4 OH (AH) and (NH 4 ) 2 CO 3 (AC). The AS treatment formed an equal molar amount of CaSO 4, which increased the mobility of ammonium, while AH and AC treatments caused Ca precipitation and decreased ammonium mobility. Leaching the AS system before NH 3 loss could occur resulted in the most rapid nitrification rate. Lower nitrification rates were found with AH and AC than AS under the same conditions. Surface placement of NH 4 fertilizers resulted in variable leachate contents of Ca + Mg. Ammonium sulfate reacted with CaCO 3 either to solubilize some Ca + Mg or simply to replace exchangeable Ca + Mg with NH 4, while AH, AC, and (NH 4 ) 2 HPO 4 (DAP) precipitated essentially an equivalent molar amount of soluble and adsorbed Ca + Mg. Use of NH 4 NO 3, which does not form an insoluble calcium precipitate, resulted in the leaching of an equivalent molar amount of exchangeable Ca + Mg from the Harkey soil. Sumber: ….. Diunduh 15/3/2012

55 MEMPERTAHANKAN KETERSEDIAAN FOSFAT. Kehilangan & Penambahan P-tersedia P-tersedia dalam tanah Sisa tanaman Pukuk kandang Pukuk komersialMineral P-tanah Bahan Organik Tanah Terangkut tanaman Hilang Pencucian Hilang Erosi Fiksasi

56 Grant, C., Bittman, S., Montreal, M., Plenchette, C. and Morel, C. Soil and fertilizer phosphorus: Effects on plant P supply and mycorrhizal development. Can. J. Plant Sci. 85: 3– ABSTRACT Plants require adequate P from the very early stages of growth for optimum crop production. Phosphorus supply to the crop is affected by soil P, P fertilizer management and by soil and environmental conditions influencing P phytoavailability and root growth. Phosphorus uptake in many crops is improved by associations with arbuscular mycorrhizal fungi. Cropping system and long-term input of P through fertilizers and manures can influence the amount and phytoavailability of P in the system and the development of mycorrhizal associations. Optimum yield potential requires an adequate P supply to the crop from the soil or from P additions. Where early-season P supply is low, P fertilization may improve P nutrition and crop yield potential. Alternately, under low-P conditions, encouragement of arbuscular mycorrhizal associations may enhance P uptake by crops early in the growing season, improving crop yield potential and replacing starter fertilizer P applications. Soil P supply that exceeds P requirements of the crop may preclude mycorrhizal development. To encourage arbuscular mycorrhizal association, threshold levels of soil solution P that restrict mycorrhizal development must not be exceeded. Sustainable P management practices must be applied both in conventional and in alternative biologically based agricultural systems. Sumber: ….. Diunduh 15/3/2012

57 Soil and fertilizer phosphorus: Effects on plant P supply and mycorrhizal development by C Grant, S Bittman, M Montreal, C Plenchette, C Morel Canadian Journal of Plant Science (2005) Volume: 85, Issue: 1, Pages: 3-14 ABSTRACT Plants require adequate P from the very early stages of growth for optimum crop production. Phosphorus supply to the crop is affected by soil P, P fertilizer management and by soil and environmental conditions influencing P phytoavailability and root growth. Phosphorus uptake in many crops is improved by associations with arbuscular mycorrhizal fungi. Cropping system and long-term input of P through fertilizers and manures can influence the amount and phytoavailability of P in the system and the development of mycorrhizal associations. Optimum yield potential requires an adequate P supply to the crop from the soil or from P additions. Where early-season P supply is low, P fertilization may improve P nutrition and crop yield potential. Alternately, under low-P conditions, encouragement of arbuscular mycorrhizal associations may enhance P uptake by crops early in the growing season, improving crop yield potential and replacing starter fertilizer P applications. Soil P supply that exceeds P requirements of the crop may preclude mycorrhizal development. To encourage arbuscular mycorrhizal association, threshold levels of soil solution P that restrict mycorrhizal development must not be exceeded. Sustainable P management practices must be applied both in conventional and in alternative biologically based agricultural systems. Sumber: ….. Diunduh 15/3/2012

58 The Effect of Farmland Management on Soil Phosphorus Runoff in Taihu Basin* Lixia YANG Journal of Cambridge Studies. Vol.6 No ABSTRACT Phosphorus fertilizer levels related to the soil phosphorus loss directly. The studies assessed the effects of different phosphorus (P) fertilizer levels (0, 30, 75 and 150 kg/hm2) on characteristics and forms of soil P loss in runoff by artificial rainfall simulations. N, P and K fertilizers were used as basal fertilizers by surface broadcast. Each treatment had three replicates of rectangular 1 × 2 m with a random block design. Slope gradient was 7% and vegetable coverage density was uniform. Two day after fertilizer application to plots, rainfall was applied using the rainfall simulator at 1.67 mm/min (100 mm/h). It lasted for 30 min after effective runoff generation. Each sample was collected on a 5 min interval for the full 30 min of the runoff event. The results indicated that P concentrations of different forms in runoff were high at the early stage, then gradually decreased with time and finally reached a comparative steady stage after about 20 min of runoff generation. At the entire rainfall-runoff process, Particulate phosphorus (PP) occupied 72%~87% of total phosphorus (TP). This showed PP was main loss form of soil P. Flow-weighted mean concentrations of soil P loss at different P fertilizer levels followed the order from large to small: 150 kg/hm2 >75 kg/hm2 >30 kg/hm2 > treatment (0 kg/hm2). It was found that the runoff losses of dissolved phosphorus(DP), dissolved inorganic phosphorus(DIP), PP and TP in runoff significantly increased in linear function with P fertilizer increase at different P fertilizer levels (r2=0.99, 0.98, 0.89 and 0.93). Sumber: ….. Diunduh 15/3/2012

59 KETERSEDIAAN KALIUM Tanah mineral umumnya mengandung cukup banyak kalium, kisaran 40 ton setiap hektar lapisan olah tanah. Namun demikian hanya sebagian kecil yangtersedia bagi tanaman Kehilangan & Penambahan Kalium: K-tersedia tanah Pupuk komersial Sisa tanaman & Pupuk Kandang Mineral-K lambat tersedia Terangkut tanaman Kehilangan pencucian Kehilangan erosi Kehilangan Fiksasi

60 Potassium Releasing Capacity in Some Soils of Anantnag District of Kashmir. Subhash Chand and Tahir Ali Universal Journal of Environmental Research and Technology Volume 1, Issue 3: Abstract The potassium releasing capacity of fifteen soil samples of Anantnag district of Kashmir were assessed by using five chemical extractants. The decreasing order of potassium release by the different chemical extractants in the soils was 1M HNO3 > 0.01 N HCl--12 extractions>0.01 N HCl--9 extractions> 0.3 N NaTPB-16 hours > 0.01N HCl 3 extractions> 1.38N H2SO4=0.01N HCl-1 extractions> % K saturation. The K released by 1M HNO3 was significantly correlated with 1.38N H2SO4 (0.995**) and N H2SO4 (0.996**). The significant correlations among different form of K in Anantnag soils indicate the various K pools (exchangeable=Non- exchangeable) for proper K fertilizer management. The potassium status in Anantnag soils was variable. Sumber: Diunduh 15/3/2012 Faktor yang mempengaruhi ketersediaan K 1.Soil CEC: Plant-available soil K is in the ionic (electrically charged) form. This charge is positive, making K a cation, represented as K +. Cations are attracted to, and held by negatively charged colloids (primarily clay and organic matter) that make up the cation exchange capacity (CEC) of the soil. The larger the CEC, the more K that can be held by the soil and the higher the soil test needed to adequately feed plants. 2.Soil test K:Higher soil test K increases the available K, by increasing the amount and balance of K relative to other cations. 3.Cation Balance: Where there is a significant imbalance between available K and the other major cations (Primarily Calcium, Magnesium, and sometimes Hydrogen, Aluminum, or Sodium), it may affect the availability of K to the crop. 4.Soil Moisture: K is transported within the soil and is absorbed by plant roots in the soil water. Therefore a water deficiency results in less K absorption. 5.Soil pH: As the soil pH is reduced (increasing soil acidity) the availability of K is often reduced. 6.Soil Temperature: Cold soils often reduce the availability of K. 7.Soil compaction: Compacted soils often reduce the availability of K. 8.Soil Drainage/Aeration: As soil drainage is improved, K uptake typically improves. 9.Soil Salinity: Saline soils often have excess sodium (Na). One of the negative effects of excess Na is that it reduces the availability of K. (sumber: Diunduh 21/3/2012)

61 RATE OF RELEASE OF NON-EXCHANGEABLE POTASSIUM BY ONTARIO SOILS IN RELATION TO NATURAL SOIL CHARACTERISTICS AND MANAGEMENT PRACTICES H. B. McEwen, B. C. Matthews Canadian Journal of Soil Science, 1958, 38(1): Abstract The rate of release of non-exchangeable potassium, i.e. potassium-supplying power, of 41 Ontario soils was measured by a continuous percolation procedure. It was found that clay content of the soil was the predominant factor affecting potassium-supplying power (r = 0.978). Potassium fertilization or intensive cropping of the soil caused no change in the potassium-supplying power of the soil. As potassium-supplying power was found to be a constant characteristic of soil and not a function of previous management, potassium-supplying power measurements should not be necessary in routine soil testing. Knowledge of potassium-supplying power can be deduced from particle size distribution. Because soils of different texture have different potassium-supplying power, the interpretation of measured exchangeable potassium in terms of fertilizer requirement will be different for soils of different textural class. Sumber: Diunduh 15/3/2012 Relationship among unavailable, slowly available, and readily available potassium in the soil-plant system. (sumber: /dc6794.html….. diunduh 21/3/2012)

62 Effect of Potassium on Potato Tuber Production in Acid Soils of Malepatan, Pokhara B.H. Adhikari, K.B. Karki Nepal Agriculture Research Journal Vol pp Abstract Soils of Pokhara valley, especially Malepatan, are fine textured silt loam, extremely acidic in nature ( pH) and are medium in soil potassium content. On-station experiments were conducted to assess the response of potassium (K 2 O) and its application methods on potato tuber yield in an extremely acid soil condition. Six potassium levels (0, 50, 75, 100 kg ha -1 as basal application, 50 kg basal plus 50 kg top dressed, and 50 kg basal plus 50 kg foliar application) were tested in the experiment for three consecutive years (2000, 2001 and 2002). A randomized complete block design (RCBD) with 3 replications was employed. Variety used was MS 42. Nitrogen (N), phosphorus (P 2 O 5 ) and compost were applied as basal dose in each plots at the rate of 100 kg, 50 kg and 20 t ha -1, respectively. Three years mean result on the plant growth characters revealed that tallest plant height was recorded (33.22 cm) when 50 kg ha -1 potassium was applied basally and 50 kg ha -1 top-dressed. The trend was quite similar in tillers production (6.96 branches plant -1 ) and biomass production ( g plant -1 ). Maximum of g plant -1 of tubers was produced when 100 kg of potassium was applied basal single dose. Highest tuber yield of t ha -1 of tuber were produced when 50 kg potassium was applied basally and 50 kg top- dressed, a total of 100 kg ha -1. Highly significant response of potassium levels on tuber production was observed in all the years. The results of this investigation suggested that application of potassium (K 2 O) at the rate of 50 kg ha -1 basal and 50 kg ha -1 top-dressed in 45 days could increase potato tuber yield satisfactorily in extremely acid soil condition. Sumber: Diunduh 17/3/2012

63 Potassium Fixation and Charge Characteristics of Clay in some Soils of Central and Northern Iran A. Hosseinpur and M. Kalbasi JWSS - Isfahan University of Technology, 2001; 5 (3) :79-93 Abstract Potassium fixation and release by phillosilicate clay minerals in soils are very important processes influencing the availability of K to plants. This investigation was conducted to determine the potassium fixation capacity and charge characteristics of soil clays of 15 surface soils (0-30 cm) from central and northern Iran. After clay particle separation, both total and tetrahedral cation exchange capacity of soil clays were determined. Tetrahedral CEC was measured after saturation with Li and heating at 300 C to reduce octahedral charge to near zero. Potassium fixation was obtained in both wet (1:10 soil:solution, 16 h on a shaker) and dry conditions (after drying for 24 h at 70°C) using three different levels of added K The total CEC in soil clays of Isfahan, Char-Mahal and Gilan provinces ranged from , and cmol kg -1, respectively. Tetrahedral CEC in soil clays of Isfahan, Char-Mahal and Gilan provinces ranged from , and cmol kg -1, respectively, which consisted of , and % of their total charge, respectively. Sumber: …http://jstnar.iut.ac.ir/browse.php?a_code=A &slc_lang=en&sid=1.. Diunduh 17/3/2012 The amount of K fixation increased with drying and the level of k added. Mean potassium fixation in soil clays of Isfahan, Char-Mahal and Gilan ranged from , and , respectively. Mean potassium fixation by soil clays (except for soil clays of Gilan) best correlated with total CEC. In the soil clays of Isfahan, mean potassium fixation correlated with tetrahedral CEC, whereas no correlation was observed in soil clays from other places. The average amount of potassium fixation in clay fractions was in the order: Gilan clays > Char-Mahal clays > Isfahan clays.

64 Factors of soil potassium regime in intensive fertilization. Hudcová, O. Journal Rostlinná Výroba 1990 Vol. 36 No. 2 pp Abstract The effects on soil potassium dynamics of applications of high doses of mineral and organic fertilizers over 21 years were evaluated for a brown earth on loess. Over this period, the mobile potassium supply of the control was not reduced, because of the soil's considerable buffer capacity; gradually, the level of available potassium fell slightly and the buffer capacity was reduced. With intensive fertilizer application, the potassium capacity factor increased by 50%, availability by 120% and mobile forms by 200%. Mineral fertilizer application increased potassium mobility, its migration to subsoil horizons and mobilization from soil resources. Organic fertilizers, however, favoured fixation on humus. Long-term application of high rates of organic and mineral fertilizers on brown earths saturated by sorption causes non-productive intake of potassium by plants, which can be partly mitigated by increasing buffer capacity. Sumber: Diunduh 17/3/2012

65 Potassium Leaching as Affected by Soil Texture and Residual Fertilization in Tropical Soils Ciro Antonio Rosolem, Thomaz Sgariboldi, Rodrigo Arroyo Garcia & Juliano Carlos Calonego. Communications in Soil Science and Plant Analysis Volume 41, Issue 16, pages Abstract Potassium (K) leaching is affected by soil texture and available K, among other factors. In this experiment, effects of soil texture and K availability on K distribution were studied in the presence of roots, with no excess water. Soils from two 6-year field experiments on a sandy clay loam and a clay soil fertilized yearly with 0, 60, 120, and 180 kg ha −1 of K 2 O were accommodated in pots that received 90 kg ha −1 of K 2 O. Soybean was grown up to its full bloom (R2). Under field conditions, K leaching below the arable layer increased with K rates, but the effect was less noticeable in the clay soil. Potassium leaching in a sandy clay loam soil was related to soil K contents from prior fertilizations. With no excess water, in the presence of soybean roots, K distribution in the profile was significant in the lighter textured soil but was not apparent on the heavier textured soil. Sumber: Diunduh 17/3/2012

66 Jurnal Ilmu Tanah & Lingkungan, Vol 9, No 1 (2007). Phosphorus and Potassium Status in Paddy Soils (Sawah) of Central Lampung Regency Junita Barus Abstract The knowledge about the nutrient status in the lowland soils is one of several ways to maintain soil fertility and increase farmers income. The objective of this study was to evaluate the status of P2O5 and K2O content in paddy soils (sawah) at Central lampung regency during the year 2001/2002. Composite soil samples were collected in each different soil types based on mapping technical survey of I : scale. Composite soil samples consisting of sub samples were taken from top layer ( em) depth. Soil sampling was taken by using grid system, that is 1 cm2 in the map represented 25 ha in the field P2O5 and K2O potential content determined by HCl 25 %. Data were arranged in a descriptive methode and then classified in to three degrees (high, medium and low). High P was > 40 mg P2O5/100 g, medium P was mg P2O5/100 g and law P was 20 mg K2O/100 g, medium K was mg K2O /100 g and low K (< 10 mg K2O/100g). The results showed that soil P2O5 status in paddy soils (sawah) of Centra Lampung regency were 61,65 % high, 35,84 % medium and 2,65 % low while K2O status were 6,64% high, 16,02 % medium and 77,34% low. Sumber: ….. Diunduh 17/3/2012

67 Clays and Clay Minerals, 1970, Vol. 18, pp FACTORS AFFECTING POTASSIUM FIXATION AND CATION EXCHANGE CAPACITIES OF SOIL VERMICULITE CLAYS ISAAC BARSHAD and FAWZY M. KISHK Abstract Soil vermiculite clays of varying tetrahedral and octahedral composition and cation exchange capacity (CEC) were examined for their ability to fix K § in both the wet and dry states. Fixation capacity, expressed as per cent of the CEC, in the wet state was fairly high for most samples but it was enhanced greatly upon drying the K saturated samples. This enhancement indicated that each sample contained a number of vermiculite species with different CECs. The vermiculite clays, as a group, exhibited a much higher fixation capacity at a much lower CEC than those of the coarse grained vermiculites. This enhanced fixation is believed due to the dioctahedral nature of the coarse grained vermiculites. In samples of nearly equal CECs only those containing AP § in tetrahedral positions exhibited an enhanced fixation capacity in the dry state but not in the wet state. In was remarkable to find that the state of oxidation of crystal structure iron strongly affected the fixation and the CEC. Reduction of Fe z+ to Fe z+ caused a decrease infixation even though the CEC increased as a result of this change. Conversely these reactions and their effects were found to be reversible. The variation in the orientation of the dipole of the hydroxyl ion in the octahedral layer with respect to the cleavage plane of the crystal is believed to be responsible for some of the noted differences. Sumber: ….. Diunduh 17/3/2012

68 The Soil Food Web In 1 teaspoon of soil there are… 5 or more Earthworms Up to 100 ……………. Arthropods 10 to 20 bacterial feeders and a few fungal feeders ……. Nematodes Several thousand flagellates & amoeba One to several hundred ciliates ……. Protozoa 6-9 ft fungal strands put end to end ………. Fungi 100 million to 1 billion …………. Bacteria Sumber: … diunduh 18/3/2012 A Soil Foodweb Audit will provide a detailed analysis of the actual and desired biomass and balance of bacteria, fungi, protozoa, nematodes, mycorrhizal fungi and microarthropods in your soil together with notes and recommendations for feeding your soil for a balanced Soil Foodweb.

69 Classical C Pools Nonhumic substances—carbohydrates, lipids, proteins Humic substances—humic acid, fulvic acid, humin BOT berpengaruh terhadap: -Plant nutrition -Soil and Plant health -Soil physical, chemical and biological properties Graph of Relative Available N with Length of Time for Decomposition Gambar diambil dari: Understanding Soil Microbes and Nutrient Recycling (James J. Hoorman and Rafiq Islam The Ohio State University) Sumber: …. Diunduh 18/3/2012

70 BOT FRAKSI RINGAN The light fraction (LF) with a density of ~1.6 gm cm-3 is relatively mineral free and consists of partially decomposed plant material, fine roots and microbial biomass with a rapid turnover time. The LF is a source of readily mineralizable C and N, accounts for ~50% of total soil C and declines rapidly under cultivation. Effect of C / N ratio on rate of decomposition of residues Sumber: Diunduh 18/3/2012

71 71 BOT --- FRAKSI BERAT --- The Heavy Fraction The heavy fraction (HF) is organic matter adsorbed onto mineral surfaces and sequestered within organomineral aggregates. The HF is less sensitive to disturbance an chemically more resistant than the LF. Effect of the C / N of incorporated residue on available N in the soil. Sumber: Diunduh 18/3/2012

72 Bacteria vs. Fungi Bacteria are smaller than fungi and can occupy smaller pores and thus potentially have greater access to material contained within these pores. Bacteria are less disrupted than are fungi by tillage practices commonly used in agriculture. Constituents Microorganisms BacteriaFungiActinomycetes Cellulose Achromobacter, Bacillus, Cellulomonas, Cellvibrio, Clostridium, Cytophaga, Vibrio Pseudomonas, Sporocytophaga etc. Aspergillus, Chaetomium, Fusarium, Pencillium Rhizoctonia, Rhizopus, Trichoderma, Verticilltttm. Micromonospora, Nocardia Streptomyces, Thermonospora Hemicellulose Bacillus, Achromobacter, Cytophaga Pseudomonas, Erwinia, Vibrio, Lactobacillus Aspergillus, Fusarium, Chaetomium, Penicillium, Trichoderma, Humicola Streptomyces, Actinomycetes Lignin Flavobacterium, Pseudomonas, Micrococcus, Arthorbacter, Xanthomonas Humicola, Fusarium Fames, Pencillium, Aspergillus, Ganoderma Streptomyces, Nocardia StarchAchromobacter, Bacillus, Clostridium Fusarium, Fomes, Aspergillus, Rhizopus Micromonospora, Nocardia, Streptomyces, PectinBacillus, Clostridium, PseudomonasFtisarium, Verticillum Chitin Bacillus, Achromobacter, Cytophaga, Pseudomonas Mucor, Fusarium, Aspergillus, Trichoderma Streptomyces, Nocardia, Micromanospora Proteins & Nucleic acids Bacillus, Pseudomonas, Clostriddum, Serratia, Micrococcus Penicillium, Rhodotorula,Streptomyces Bacteria are the most abundant organisms playing important role in the decomposition of organic matter. Majority of bacteria involved in decomposition of organic matter are heterotrophs and autotrophs are least in proportion which are not directly involved in organic matter decomposition. Actinomycetes and fungi are also found to play important role in the decomposition of organic matter. Soil algae may contribute a small amount of organic matter through their biomass but they do not have any active role in organic matter decomposition. Sumber:

73 Bacteria vs. Fungi Fungi tend to be selected for by plant residues with high C/N ratios. Fungi have a greater influence on decomposition in no-till systems in which surface residues select for organisms that can withstand low water potentials and obtain nutrients from the underlying soil profile. Decomposition of Cover Crop Residues: Cowpeas with a low C:N ratio ( 38) will decompose slowly (3 months to 1 year or more) and will result in net immobilization or will tie up soil N. Graph by Dr. Rafiq Islam. Gambar diambil dari: Understanding Soil Microbes and Nutrient Recycling (James J. Hoorman and Rafiq Islam The Ohio State University) Sumber: …. Diunduh 18/3/2012

74 74 Bacteria vs. Fungi Fungi often produce more cell wall than cytoplasmic material when starved for N, and thus can extend into new regions of the soil without requiring balanced growth conditions. The filamentous growth structure of a fungus permits it to access C in one location and nutrients in another. Soils contain about 8 to 15 tons of bacteria, fungi, protozoa, nematodes, earthworms, and arthropods. See fact sheets on Roles of Soil Bacteria, Fungus, Protozoa and Nematodes. Understanding Soil Microbes and Nutrient Recycling (James J. Hoorman and Rafiq Islam The Ohio State University) Sumber: …. Diunduh 18/3/2012

75 KANDUNGAN BOT How organic matter in soil influences the soil-plant relationship? Decomposed organic matter provides nutrients for plant growth (Mineralization) It determines the soil’s temperature, air ventilation, structure and water management It contains bioregulators which affects plant growth It contains bioregulators, which affects plant growth (enzymes, hormones, etc.) Its carbon and energy content is the soil’s energy battery for future use It determines the soil’s capacity to compensating, regenerating and protecting the environment regenerating and protecting the environment. It is widely recognized that SOM plays an important role in soil biological (provision of substrate and nutrients for microbes), chemical (buffering and pH changes) and physical (stabilization of soil structure) properties. In fact, these properties, along with soil organic carbon (SOC), N and P, are considered critical indicators for the health and quality of the soil. (sumber: nicmatter.html….. Diunduh 21/3/2012)

76 76 PENTINGNYA BOT 1.Organic material in the soil is essentially derived from residual plant and animal material, synthesised by microbes and decomposed under influence of temperature, moisture and ambient soil conditions 2.Soil organic matter is extremely important in all soil processes 3.Cultivation can have a significant effect on the organic matter content of the soil 4.In essentially warm and dry areas like Southern Europe, depletion of organic matter can be rapid because the processes of decomposition are accelerated at high temperatures 5.Generally, plant roots are not sufficiently numerous to replace the organic matter that is lost Memperbaiki Kandungan BOT There are many management practices you can do to improve SOM on your property. Practices that may increase soil organic matter include: 1.Meminimumkan pengolahan tanah 2.Memelihara vegetasi penutup tanah 3.Melindungi tanah dari kebakaran 4.Stubble retention 5.Menambahkan pupuk kandang atau bahan organik lainnya 6.Membatasi grazing 7.Mengendalikan serangga dan rodents (http://vro.dpi.vic.gov.au/dpi/vro/vrosite.nsf/pages/soilhealth_practical-note-soil-organic-matter ….. Diunduh 19/3/2012)

77 MANFAAT BOT 1.Storehouse for nutrients 2.Source of fertility 3.Contributes to soil aeration thereby reducing soil compaction 4.Important ‘building block’ for the soil structure 5.Aids formation of stable aggregates 6.Improves infiltration/permability 7.Increase in storage capacity for water. 8.Buffer against rapid changes in soil reaction (pH) 9.Acts as an energy source for soil micro-organisms Sumber: …. Diunduh 18/3/2012 Understanding Soil Microbes and Nutrient Recycling (James J. Hoorman and Rafiq Islam The Ohio State University)

78 Degradation: HILANGNYA BOT 1.During field operations, fresh topsoil becomes exposed and dries rapidly on the surface 2.Organic compounds are released to the atmosphere result from breakdown of soil aggregates bound together by humic materials 3.Unless the organic matter is quickly replenished, the system is in a state of degradation leading eventually to un- sustainability 4.The removal of crop residues in dry ecosystems, which are inherently marginal, can cause such systems to be quickly transformed from a stage of fragility to total exhaustion and depletion Long-term effect of tillage, crop rotations and fertilizer application on soil organic matter. Sumber: Diunduh 18/3/2012

79 FAKTOR YG PENGARUHI BOT Faktor-faktor Alamiah: 1.Iklim 2.Soil parent material: acid or alkaline (or even saline) 3.Land cover and or vegetation type 4.Topography – slope and aspect Human-induced factors: 1.Land use and farming systems 2.Land management (cultivation) 3.Land degradation The source of SOM Plants are able to harvest energy from sunlight by making carbohydrates from carbon dioxide and water. This is photosynthesis and provides the energy for powering ecosystems. Plant (and animal) residues then become available for soil organisms to feed on, metabolise and produce new residues. These new residues then become the food source for yet more organisms – and so on. The pathway for the break down of plant matter (Brady, 1990)

80 FAKTOR IKLIM PENGARUHI BOT: Temperature: OM decomposition rapid in warm climates OM Decomposition is slower for cool regions Result: Within zones of uniform moisture and comparable vegetation -- Av total OM increases 2x to 3x for each 10 deg C fall in mean temperature Moisture: OM decomposition rapid in warm climates OM Decomposition is slower for cool regions Result: Under comparable conditions Av total OM increases as the effective moisture increases AIR TANAH SUMBER: …. DIUNDUH 18/3/2012 Adequate soil moisture i.e. about 60 to 80 percent of the water-holding capacity of the soil is must for the proper decomposition of organic matter. Too much moisture leads to insufficient aeration which results in the reduced activity of microorganisms and there by checks the rate of decomposition.

81 81 Sumber: pgsgrow.com/blog/tag/organic-gardening/ C: N ration of organic matter has great influence on the rate of decomposition. Organic matter from diverse plant-tissues varies widely in their C: N ratio (app %). The optimum C: N ratio in the range of is ideal for maximum decomposition, since a favorable soil environment is created to bring about equilibrium between mineralization and immobilization processes. Thus, a low nitrogen content or wide C'.N ratio results into the slow decomposition. Protein rich, young and succulent plant tissues are decomposed more rapidly than die protein-poor, mature and hard plant tissues. Therefore, C:N ratio of organic matter as well as soil should be narrow/less for better and rapid decomposition. Thus, high aeration, mesophilic temperature range, optimum moisture, neutral/alkaline soil reaction and narrow C: N ratio of soil and organic matter are required for rapid and better decomposition of organic matter. C/N ratio SUMBER: …. DIUNDUH 18/3/2012

82 Structure of soil, indicating presence of bacteria, inorganic, and organic matter Sumber: Good aeration is necessary for the proper activity of the microorganisms involved in the decomposition of organic matter. Under anaerobic conditions fungi and actinomycetes are almost suppressed and only a few bacteria (Clostridium) take part in anaerobic decomposition. The rate of decomposition is markedly retarded. It was found that under aerobic conditions 65 percent of the total organic matter decomposes during six months, while under anaerobic conditions only 47 percent organic matter can be decomposed during the same period. Anaerobic decomposition of organic matter results into the production of large quantity of organic acids and evolution of gases like methane (CH 4) hydrogen (H2) and carbon dioxide (CO2). Aerasi Tanah SUMBER: …. DIUNDUH 18/3/2012

83 PUPUK KANDANG Manure consists of animal excrement, usually mixed with straw or leaves. The amount and quality of the excrement depend on the animals. feed. Good manure contains more than just excrement and urine. Straw and leaves are added and it is aged. Ageing is necessary to retain all of the nutrients. Using aged manure is an ideal method to retain and increase soil fertility. Tujuan aplikasi pupuk kandang: 1.Meningkatkan kandungan BOT; 2.Meningkatkan hara tersedia dalam tanah; 3.Memperbaiki struktur tanah (aggregasi tanah) dan kemampuan tanah menyimpan air. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, 2004.

84 KEUNTUNGAN MENYIMPAN DAN MEMATANGKAN PUPUK KANDANG Fresh stable manure is not very suitable for immediate use. The C:N ratio of fresh manure is high, which can cause nitrogen immobilisation. If the organic matter is very rough i.e. it contains a lot of fibre and few fresh, juicy leaves then the C:N ratio is high. Microorganisms then have to work hard to digest it and allow nutrients to become available to the crops. Moreover the micro-organisms use nutrients to build up their own bodies which may exceed temporarily the amount they can generate. Also, in the initial stage of decomposition, substances are freed that can inhibit plant growth or scorch the leaves. If the manure is spread on a field empty of crops, many nutrients will be leached. Often there is not even a field immediately available where manure could be spread. Keeping and ageing the manure has a number of advantages: ? The C:N ratio decreases during ageing. ? Harmful substances that are released in the first stage of decomposition are eliminated. ? Weed seeds are decomposed or loose their germinative power. ? Few nutrients are lost through run-off or volatilisation. ? Aged manure is easier to transport. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, 2004.

85 KOMPOS Compost is an ideal fertiliser. To create a compost heap, organic material (e.g. crop residues, straw, manure, kitchen wastes, etc.) is collected and stored together. In this heap micro-organisms decompose the material. Graph of Cowpeas (C:N<20) being decomposed by bacteria and fungus, the carbon dioxide evolution and protozoa and nematodes consuming the bacteria and fungus and excreting ammonia into the soil for plant growth. NO3- and NH4+ are easily converted in the soil. Graph by Dr. Rafiq Islam. Gambar diambil dari: Understanding Soil Microbes and Nutrient Recycling (James J. Hoorman and Rafiq Islam The Ohio State University) Sumber: …. Diunduh 18/3/2012

86 KEUNTUNGAN KOMPOSTING Compost increases the level of organic matter in the soil, which has a positive effect on the soil organisms, soil structure, infiltration, water retention capacity and aggregate stability. Compost is rich in nutrients that are readily available to the plants. Advantages of compost over mulch or green manures: 1.Through composting, diseases and pests, as well as weed seeds are destroyed because the temperature in the compost heap is so high that they cannot survive. 2.Rats and mice can nest in thick layers of leaves or mulch. This is not a problem with compost. 3.If green manures are ploughed into the soil in climates that have a heavy rainy season, the mineralised nitrogen can be leached or volatilised (denitrification). 4.Some materials have a very high C:N ratio, which can result in the immobilisation of nitrogen. After composting, the C:N ratio is decreased and the rough material is largely decomposed. 5.Nutrients and organic material are lost when crop residues or fallow vegetation are burned. The positive effects of the ash often last only one season. By composting the material the nutrients and the organic matter is preserved and the positive effects last much longer. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, 2004.

87 KETERBATASAN KOMPOSTING 1.Composting is labour-intensive. If labour is in short supply, this can be an important limiting factor. On the other hand, compost is such a valuable fertiliser that it makes the invested labour very costeffective. 2.The compost heap can also be made in a period when there is not very much other work to be done. 3.Another limitation can be that organic material is scarce, or it is used for cooking fuel. This can be solved by planting trees for firewood, for example as a living fence. Composting without manure is very difficult, but it is possible. 4.A compost heap can attract vermin, especially if kitchen scraps are also used. It can also stink. This need not be a problem if the heap is kept in the field instead of in the farmyard. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, Kelemahan Pembuatan Kompos: 1.Loss of Ammonia : Compost contains less than half the nitrogen of manure but if manure is not incorporated into the soil it loses nitrogen to the atmosphere and may retain less nitrogen than the compost. 2.Time Involved : Composting requires a time commitment to properly manage the windrows to produce quality compost. 3.Cost of Equipment : Specialized windrow turners may be required, but they can come at with a high price tag. 4.Land Required : The composting site and storage for finished product can use a considerable area of land. 5.Marketing Required For Sale : Money and time may be spent advertising, packaging, and managing the business. (http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/eng4464/$file/comp_benefits.pdf?OpenElement)

88 KESEIMBANGAN HARA To ensure a sufficient nutrient supply for crops, we must strive to keep an even nutrient balance in the soil. The loss of nutrients has to be minimised, and the addition of nutrients maximised in order to avoid a depletion of nutrients in the soil. Kehilangan hara dari tanah dapat terjadi melalui proses-proses berikut: 1.removal of the harvest (all of the nutrients); 2.volatilisation (especially N; this happens especially during burns due to the high temperatures); 3.run-off (especially N); 4.fixation (especially P); 5.leaching; 6.erosion (all nutrients). Hara ditambahkan ke tanah melaluii proses: 1.decomposition of organic matter (all nutrients); 2.nitrogen fixation (only N); 3.weathering (mostly K and Mg); 4.chemical fertiliser (mostly N, P, and K); 5.rain and solid matter deposits. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, 2004.

89 PUPUK HIJAU Green manuring consists of ploughing in green, not woody plants or plant parts. The plant material can come from a crop that was grown after or between the main crop, or from a weed that grew during a fallow period. It can also come from a shade plant or tree whose cuttings or fallen leaves are suitable for ploughing into the soil. Tujuan penggunaan pupuk hijau adalah untuk: 1.make nutrients available for the main crop; 2.improve the soil structure; 3.increase or retain the level of organic matter in the soil; 4.increase the ability of the soil to retain moisture; 5.protect the soil against rain and wind erosion, dehydration and extreme temperature fluctuations at a time when no other crops are present; 6.when using leguminous plants as green manure, to fix extra nitrogen out of the air, which becomes available to the main crop after the manure has been ploughed into the soil. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, 2004.

90 KEUNTUNGAN PUPUK HIJAU Keuntungan Pupuk Hijau 1.During their growth period, green manures provide the same benefits as mulch. They are therefore sometimes called.living mulch.. 2.Their advantage over mulch is that they absorb nutrients, so these cannot be leached during a period in which no main crops are grown. After the green manures are ploughed under, these nutrients become available via decomposition. 3.Green manures also have a positive effect on the soil structure, because of the penetration of their root systems, they add organic matter, and they stimulate the growth of soil organisms. Organic matter nourishes the soil organisms, which also benefit from the higher moisture content and the limiting of extreme temperatures during the day. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, Pupuk Hijau Any crop grown on land with the intent of turning it into the soil is called a green manure. Generally, legumes and various grasses are grown as green manure. Turning under a crop can provide a number of benefits, including increasing organic matter of the soil, decreasing certain disease problems, and increasing the nutrient level in the soil. After the green manure is turned under, it decomposes and adds nutrients and organic matter to the soil. (http://erthturf.com/AllAboutOrganicGardening.html... diunduh 19/3/2012)

91 KETERBATASAN PUPUK HIJAU 1.If farmers are not accustomed to growing green manures, they may not readily accept the method. While the farmers have to invest their time and labour, they receive no obvious benefit, such as cash or food. The direct advantage in the form of increased production is not always immediately noticeable. Moreover, ploughing under a green manure is hard work, especially if done by hand. 2.An alternative that is easier to introduce is intercropping with a green manure. The green manure is then grown in combination with the main crop. To prevent competition for nutrients, the green manure plant is sown later than the main crop. This is possible even in a short season, because the green manure plant does not have to mature fully. One plant that has been used quite successfully for this purpose is mucuna under corn. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, Tanaman jagung dengan pupuk hijau

92 APLIKASI PUPUK HIJAU 1.It is important to choose a plant species that quickly covers the ground and produces a deep and extensive root system, so that the nutrients from the deep soil layers can be transported to the surface. A fast groundcover also prevents the growth of weeds, because it shades them. 2.However, the green manure may not grow so quickly and easily that it expands to other fields where a different crop is being grown. And it may not be so resilient that it continues to grow after it has been ploughed under. 3.A few species that are often used as green manures are: Crotolaria juncia (sun hemp), Sesbania aculeata (daincha), Vigna unguiculata (cowpea), Vigna mungo (black gram), and Vigna radiata (green gram). If these species are not available, other species that grow well in the area can be used, as long as they satisfy the requirements listed above. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, Azolla: Profil Pupuk Hijau Azolla is a small aquatic fern (usually 1-5 cm large) which can also grow on saturated or moist soils. It is capable of doubling its weight in 3-5 days. A blue-green alga (Anabaena azollae) lives in the cavities of Azolla leaves and fixes nitrogen from the atmosphere. The daily nitrogen-fixing rate of the Azolla-algae complex is 3-7 kg N/ha. Azolla contains 4% nitrogen on a dry-weight basis (dry weight is 5% of fresh weight); % phosphorous; and 24.5% potassium. Azolla is not really new. It has been used as a green manure for rice in Northern Vietnam and Southern China as early as the 11th century. Use of Azolla is an Asian, indigenous technology. (sumber: off-0fnl direct l--11- en about utfZz-8- 00&cl=CL3.33&d=HASHd3b46cd4916b56b3547bcc.2.12& gt=1…..diunduh 21/3/2012)

93 APLIKASI PUPUK HIJAU The green manures are usually ploughed under when they are still young and succulent. The material is then broken down quickly by the soil organisms, whereby the nutrients become available. Within a few months the material is completely decomposed. Thus, little addition is made to the level of organic matter in the soil. Young and succulent material should be ploughed under at least two months before the new crop is sown, because in the initial period of decomposition, substances are released that can damage the young sprouted plants or can make the root ends sensitive to damage by pathogens. If the material is ploughed under when it is older and tougher it will be broken down much slower. In that case it does add to the level of organic matter in the soil. Since the nutrients are slowly made available, their effect in the first season is less than with young and succulent material. However, the effect is noticeable for several seasons. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, 2004.

94 APLIKASI PUPUK HIJAU Dekomposisi pupuk hijau sebelum ada tanaman pokok If the soil has a low organic content, it is better to let the green manure get old and tough, so that an addition is made to the level of organic matter in the soil. The level of organic matter in the soil is after all the most important indicator of soil fertility. Material that is old and tough generally is difficult to decompose. Many soil organisms are needed to do this. Before the soil organisms can start to digest the organic matter they have to grow themselves. To grow the organisms use nitrogen like plants do (this is also called nitrogen immobilisation). This means that if plants grow at the same time as the organisms the plants will lack nitrogen. Therefore it is better to first allow the soil organisms to grow and decompose the organic matter before the crop is sown. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, 2004.

95 INTERCROPPING Intercropping means growing two or more crops together on the same field. By combining crops that have different growth patterns, the available air, water and nutrients can be better utilised. Sasaran Penting intercropping : A direct production increase compared to monoculture (if enough water is available), due to: 1.Menutupi muka lahan dnegan lebih baik; 2.Pemanfaatan radiasi matahari secara optimal; 3.Pertumbuhan akar lebih efisien; 4.Ekstra tambahan nitrogen (kalau melibatkan penambat N2). Spreading the risks of crop failure over more crops, due to: 1.multiple crops; if one crop fails the other might still yield something; 2.limited effect of diseases and pests because one pest or disease is mostly specialised on one crop and will leave a different crop unharmed. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, Schematic representation of vertical root distribution of cacao intercropped with coconut (Nelliat et at. 1974). (http://www.fao.org/docrep/005/a f298e/af298E01.htm)

96 MANFAAT INTERCROPPING In many parts of Africa intercropping is a traditional farming method. A common combination is a grain crop grown together with a bean crop. Grains generally grow tall and slender, while beans stay low and creep over the ground. This combination protects the soil more than a single grain crop would. Grains generally need as much sun as possible, while beans and other legumes grow just as well in the shade. The available sunlight can thus be utilised optimally by both crops. 1.If one of the crops fails, for example due to irregular rainfall or disease, then the other crop can often still provide a successful harvest. In this way, the farmer minimises the risks of crop failure. 2.With multiple crops, each with its own root pattern, water and nutrients can be absorbed from various layers and places. These resources are thus utilised more efficiently than when only one crop is grown. 3.Intercropping can have a limiting effect on the spread of diseases and pests. For example, grains can serve as a barrier against the spread of insects in cowpea or peanut crops. 4.Insects or other pests that damage a particular crop can be driven away by substances that another crop produces, or by the other crop.s attraction of insects that eat the damaging soil organisms or insects. This method is especially used in the cultivation of vegetables, such as by planting onions and carrots next to each other. 5.Lack of labour is often a problem at peak seasons such as sowing and harvesting time. If the sowing and harvesting periods of the different crops vary, it is easier to spread the available labour over the entire season avoiding high peaks Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, 2004.

97 KERUGIAN INTERCROPPING 1.One disadvantage is that the denseness of the crops makes it physically more difficult to combat diseases, pests and weeds. 2.Mechanisation of an intercropping system is difficult to achieve. However, this is generally not a very serious problem because small farmers perform most tasks by hand. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, Yield decreases as the crops differ in their competitive abilities. 2.Management of I/c having different cultural practices seems to be difficult task. 3.Improved implements cannot be used efficiently. 4.Higher amount of fertilizer or irrigation water cannot be utilized properly as the component crops vary in their response of these resources. 5.Harvesting is difficult. (http://www.agriinfo.in/?page=topic&superid=1&topicid=662) Kerugian Intercropping:

98 METODE INTERCROPPING 1.A frequently used combination is that of a grain with a bean. Beans are nitrogen fixing crops i.e. they can fix extra nitrogen from the air. They are also good at releasing fixed phosphate. The timing of the sowing dates of the different crops in relation to each other is important, because if the nitrogen-fixer matures and is harvested first, then the added nitrogen and phosphate already become partially available to the other crop. If it matures after the other crop, then the nitrogen and phosphate will only be available to the subsequent crop. 2.Whether diseases and pests are stimulated or, preferably, blocked by intercropping depends on the crops, the climate and also on which diseases and pests are common in the area. Therefore, it is best to first experiment on a small scale. 3.If farmers have very serious objections to growing various crops together on one field, then crop rotation is an option. In this case various crops are grown one after the other on one field. By choosing crops that have different root patterns and that do not contract the same diseases, some of the advantages of intercropping can still be achieved. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, For best ecological results, the corn and soybeans are planted at specific predetermined distances at the same time of year. The corn and soybeans create a microclimate of humidity, as well as a root system and groundcover which effectively resists drought and erosion. Another advantage is use of conservation tillage which is compatible with the ecological longterm advantages of intercropping commercial annual grains and legumes. (http://www.freepatentsonline.com/ html)

99 MULSA DAN APLIKASINYA Mulching means covering the ground with organic material, such as crop residues, straw or leaves, or with other materials such as plastic or gravel. The goal of mulching is to: 1.Improve infiltration; 2.Protect the soil from water and wind erosion and from dehydration; 3.Prevent high ground temperatures; 4.Increase the moisture level in the soil; and, when mulching with organic material, to: 5.Increase or retain the level of organic matter in the soil; 6.Better utilise the nutrients from chemical fertiliser; 7.Stimulate soil organisms. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis. Agromisa Foundation, Wageningen, Peranan Mulsa Orgfanik Mulches have many beneficial effects upon the soil, plants and area surrounding the plants. 1.They conserve soil moisture by reducing evaporation of water from the soil. 2.They prevent crusting of the soil surface, thus improving absorption and percolation of water to the soil areas where the roots are growing. 3.They maintain a more uniform soil temperature by acting as an insulator that keeps the soil warm during cool spells and cooler during the warm months of the year. 4.They prevent fruits and plants from becoming mud splashed and reduce losses from soil-borne diseases. 5.They reduce weed problems when the mulch material itself is weed-free and is applied deep enough (at least 2.5-cm thick) to prevent weed seed germination or smother existing smaller weeds. Time and labor of weeding is reduced considerably when mulches are used properly. (sumber: html….. Diunduh 21/3/2012)

100 KEUNTUNGAN MANFAAT MULSA 1.Covering the ground with a mulch layer protects the soil from forming a crust. This allows the rainwater to infiltrate, and thus decreases water erosion. Moreover, the mulch layer protects the soil particles from being carried away by strong winds, i.e. it decreases wind erosion. 2.The mulch layer protects the soil from becoming dehydrated. Together with increased infiltration, this ensures that the moisture content in the soil remains higher than in soil without a mulch layer. It will thus take longer in the dry season for crops with a mulch layer to be short of water. 3.The temperature of exposed soil can become very high during the day. By applying a mulch layer, the sun is blocked and the daytime temperature is lower, which is favourable for seed germination, the crop.s root growth, and for the growth of micro- organisms. 4.The mulch layer prevents the phosphate in chemical fertilisers from getting into contact with the soil particles that fix the phosphate. Phosphate fertilisers are therefore more effective if they are applied on top of a mulch layer than if they are applied on unprotected soil. An extra advantage of mulching with organic materials compared to mulching with non-organic materials is: the decomposition of the mulch increases the level of organic matter in the soil. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis. Agromisa Foundation, Wageningen, Effect of organic residue mulch on soil moisture storage (Juo, 1990). Juo, A.S.R. (1990) Maintenance and management of organic matter in tropical soils. In: Pushparajah, E. and Latham, M. (eds), Organic Matter Management and Tillage in Humid and Subhumid Africa. IBSRAM Proceedings No. 10, International Board for Soil Research and Management, Bangkok, Thailand, pp

101 KETERBATASAN DAN KERUGIAN MULSA 1.Some organisms in the soil can profit so much from the higher moisture content and protection from high temperatures that they proliferate under the mulch layer. Snails can multiply extremely quickly under a mulch layer. In sub-humid areas of Africa, mulching caused an increase in termites. The termites can harm the crops, coffee for example. In such circumstances, it would be better to look for an alternative, combining the use of compost with specific steps to protect the soil from water and wind erosion. 2.The use of crop residues as mulch can intensify the risk of pests. This is especially true with the crop residues of corn, sorghum, sugar cane and cotton, particularly if they are not grown alternatively with another crop. Damaging organisms such as stem borers can survive in the stems and create problems the following season. This effect can be minimised by ploughing the crop residues into the soil, by allowing cattle to graze, by adding compost, or by rotating crops. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis. Agromisa Foundation, Wageningen, Organic mulch should not touch the tree stem, particularly where rodents and insects are a problem. Where termites attack the young trees, only a non-organic mulch or plastic may be acceptable. Source: Briscoe (1989), p Briscoe, C.B Field trials manual for multipurpose tree species. Multipurpose tree species network research series; manual no. 3. Winrock International. Bangkok, Thailand. Sumber: 0hdl direct l--11-en about utfZz-8- 00&cl=CL3.58&d=HASH01c80496ecbd184652a2bf98.4>= 2….. Diuinduh 21/3/2012

102 TEKNOLOGI APLIKASI MULSA Metode dan Rekomendasi Mulsa The mulch has to be applied before the rainy season begins, because the soil is then most vulnerable. The seeds can be sown through the mulch layer by making small openings in the mulch through which the seeds are planted. After planting each seed the opening must be closed, otherwise birds will become aware of the presence of the seed. The mulch layer may not be too thick. A sufficient amount would almost completely cover the soil from sight. If the layer is too thick, it will be difficult for the sprouted plants to reach the surface. The seeds can also be sown in rows that have been cleared by ploughing or removing the mulch. Sumber: SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke Nieuwenhuis Agromisa Foundation, Wageningen, Aplikasi Mulsa Apply mulch around established plants in the garden in mid-spring, when the soil has warmed up sufficiently for active root growth. If a mulch is applied before this time, it will keep the ground cool and root development will be delayed. With newly planted material, apply a mulch after the plants are set in place and watered in well. If you are planting in the late summer or early fall, apply the mulch immediately after watering the plants so that the soil temperature will be kept warm during the cool nights. It is important for fall-planted stock to have sufficient root growth so that the plants don't heave out of the ground during the winter months because of alternate freezing and thawing. Organic mulches such as leaves, sawdust, or shredded bark should be moist when applied to the soil. Extremely dry mulches act as a blotter and remove moisture from the soil. (http://www.aces.uiuc.edu/vista/html_pubs/mulch/MULCH.html)

103 Food, Agriculture, and the Environment Discussion Paper 32 Integrated Nutrient Management, Soil Fertility, and Sustainable Agriculture: Current Issues and Future Challenges by Peter Gruhn, Francesco Goletti, and Montague Yudelman International Food Policy Research Institute K Street, N.W. Washington, D.C U.S.A. September 2000 Sistem Neraca Hara Tanaman Smaling, E. M. A Soil nutrient depletion in Sub-Saharan Africa. In The role of plant nutrients for sustainable food crop production in Sub- Saharan Africa, ed. H. Van Reuler and W. H. Prims. Leidschendan, the Netherlands: VKP. Sumber: ….. Diunduh 15/3/2012

104 Soils: Fertility Management MSU EXTENSION SERVICES October 14, Use soil testing to assess fertility status. 2.Use common-sense, attainable yield goals. 3.Determine nutrient and moisture content of manure. 4.Base nutrient applications (either manures or purchased fertilizer) on crop needs as determined by the soil test. 5.Rotate fields receiving manure to avoid nutrient buildup and maximize nutrient utilization. 6.Use only sufficient fertilizer required for attainable crop yield goals. 7.Incorporate fertilizer and manure when possible. 8.Calibrate all application equipment. 9.Avoid applying fertilizer, or manure, on wet soils to minimize compaction, runoff and leaching/denitrification. 10.Avoid applying fertilizers and manure near streams, ponds, or other water bodies. 11.Use grass filter strips along ditches and waterways to reduce soil erosion, runoff and nutrient losses. 12.Time applications to when nutrients are needed by the crop as possible. 13.Utilize fall cover crops to minimize soil erosion and runoff and to maximize nutrient utilization from manure applications. Sumber: ….. Diunduh 17/3/2012 BMP Kesuburan Tanah

105 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Nutrient Management Planning (NMP) is a Best Management Practice, or BMP. While the term “nutrient management”often is associated with manure management, it applies to all nutrient inputs, including organic materials, livestock byproducts, and inorganic commercial fertilizers. When animal manures are a nutrient source for a farm, NMP includes Comprehensive Nutrient Management Plans, or CNMP, particularly when developed by Natural Resource Conservation Service personnel. What is Nutrient Management Planning? Nutrient management planning principles are the same as good business management principles: Know what you have, Know what you need, Manage wisely, and Document the management. Nutrient management plans must be site-specific, tailored to the available inputs, soils, landscapes, and management objectives of the farm. Sumber: ….. Diunduh 17/3/2012http://msucares.com/pubs/publications/p2647.pdf#page=27

106 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Tahapan dalam Perencanaan Pengelolaan Hara 1.Obtain accurate soil information for each field or management unit. a. Create farm maps that include soil series, surface water bodies, and other resource concerns present in the landscape. b. Sample the soil in each field or management unit and process through a reputable soil-testing laboratory. 2Develop fair, realistic estimated crop yield goals for each field based on recent production history, agronomic practices, and soil characteristics. The key is to be realistic. The past three to five years of production data may be used to develop an average baseline. 3Using the soil test analyses, determine the plant nutrients required to reach the yield goal. In some cases, you may need to take into consideration nutrient uptake and removal data for common crops. 4Determine plant-available nutrients from any livestock byproduct amendments that will be used to fertilize the crop. The BMP is to sample manure that will be used. General values are available, but accurate nutrient content of manure is specific to site, animal, diet, and management. 5Estimate nutrient contributions from manures that were applied in previous seasons. Usually 50 to 60 percent of nitrogen in animal manures is available to growing plants the first year following application. Residual nutrients are usually available on a declining scale for about three growing seasons. 6Environmental assessment tools, such as the Mississippi Phosphorus Index (PI), can calculate the potential risk of offsite phosphorus movement on a field-by-field basis. The PI incorporates sitespecific soil conditions and applied BMPs in the evaluation. Soil test phosphorus levels, soil permeability, field slopes, litter application rates, distance to surface water, and other factors are used to determine the probability of nutrient movement. If the PI shows low risk, NMP may be based on crop nitrogen needs for optimal production. If the PI is medium risk, additional BMPs may be necessary. If the PI shows high potential risk for P movement in the landscape, NM should be based on crop P requirements as determined by the soil test recommendations. 7Apply animal manures and commercial fertilizers based on soil-test recommendations and the risk assessment. Over-application does not improve yields and increases the risk of environmental problems. 8Keep records of nutrient sources, application dates, rates, methods, and general climatic conditions. Good records simplify planning. Sumber: ….. Diunduh 17/3/2012http://msucares.com/pubs/publications/p2647.pdf#page=27

107 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Best Management Practices UNSUR HARA UNTUK PRODUKSI TANAMAN The soils, environment, and crop systems used in Mississippi offer unique challenges for fertilizer management. Management plans should both protect our water resources and produce agronomic crops economically. Best Management Practices (BMPs) are research-proven, achievable management options. BMPs are site-specific, depending on current and past soil management, climate, crops grown, and operator expertise. Fertilizer management has three primary goals: 1) Match fertilizer nutrients to crop nutrient requirements, 2) Manage fertilizer applications wisely, and 3) Minimize the transport of nutrients from fields to water bodies. There are five basic questions that each nutrient manager addresses in planning for the next crop: 1.Are the fertilizers necessary? 2.How much fertilizer is economical? 3.What fertilizers are available? 4.When is the best time to apply the fertilizer? 5.How can I maximize effectiveness? Sumber: ….. Diunduh 17/3/2012http://msucares.com/pubs/publications/p2647.pdf#page=27

108 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Sinkronisasi suplai hara pupuk dengan Kebutuhan Tanaman Soil testing Fields should be tested for pH, P, K, and other nutrients at least every three years and preferably more often. Analyze animal byproducts Poultry production is the only consistent source of animal byproducts available in bulk in Mississippi to provide crop nutrients. Nutrient contents vary due to different bird and litter management programs. Application rates should be based on analysis of the actual litter used. Nutrient budgeting Soil testing, manure analysis, nutrient uptake, and nutrient removal data accounts for all nutrient sources and outflows. This information makes it possible to calculate application rates, particularly if animal manures are to be used, and allows “what-if” analysis of different rate application scenarios. Develop and use realistic yield goals The Mississippi State University Extension Service bases fertilizer recommendations or N on yield goals for agronomic crops. Including yield goals makes the recommendations site-specific; soil texture differences are included in the rate calculations for cotton. Some cooler, drier states no longer use yield goals when recommending N, but yield goals are important in Mississippi, where the humid climate makes predicting levels of residual N more difficult. It is important to use realistic yield goals when you calculate application rates. Average the crop yields from the past 3 to 5 years. Add 10 percent for a realistic projection of the production potential of your soils, management, and climate. If past yields are not available, contact the local offices mentioned above for information on the specific capabilities of different soil series. Plant nutrient analysis Chemical analysis of plant nutrient concentrations in tissue, along with soil testing, may evaluate the soil fertility program and nutrient availability. It is most valuable when “good” and “bad” sections of a growing field can be contrasted. Information on plant diagnostic sampling is available at Sumber: ….. Diunduh 17/3/2012http://msucares.com/pubs/publications/p2647.pdf#page=27

109 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Aplikasi Pupuk secara Bijaksana Soil test based recommendations Each soil test phosphate and potash result is rated with a category or index. MSU uses five: very low, low, medium, high, and very high. The category compares the amount measured in the soil to the amount needed by the plants. A score of very high means plants probably will not respond to additional fertilizer; a score of very low means plants probably will respond to the addition of the nutrient. If the soil is rated high or very high, P or K fertilizers are not needed for SEVERAL crops. Medium means there may or may not be a response; for soil in this category, MSU recommends maintenance levels of P and K. Soils in the very low or low categories should respond to fertilizer; therefore, the decision depends on the relative risks of fertilizing versus not fertilizing. If the soil tests medium, low, or very low, the MSU When the soil tests high, the only agronomic crop that the MSU ES recommends K for is cotton. Research has found K stress in midseason for newer varieties. Using the right fertilizer for the situation Usually, when different fertilizer sources of the same nutrient appear to work differently, it’s because the inherent differences between the fertilizer materials are not taken into consideration. Plants cannot tell the difference between sources of a particular nutrient. Nutrient ions, such as nitrate or phosphate, are all the same when they are in the soil solution, no matter what their source. N fertilizer efficiency especially depends on the product and how it is managed. Mississippi State University Extension Service recommendations for N fertilizer management are not based on soil tests. The state is warm and humid, so N soil testing techniques have had limited usefulness. Nitrogen recommendations are based on the crop to be grown and, whenever possible, realistic yield goals. Some N fertilizers are volatile; that is, they change from urea or urea-ammonium nitrate into ammonia gas, which drifts away from the field. This loss increases when these fertilizers are applied at temperatures higher than 65 °F, on fields with a large amount of organic matter or surface residues, or in high humidity. Sumber: ….. Diunduh 17/3/2012

110 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Aplikasi Pupuk secara Bijaksana Proper placement of fertilizers Correct fertilizer placement is crucial to efficiency. Avoid broadcast sprays of UAN solutions on hot, dry days unless the material will be cultivated in, irrigated in, or rain is imminent. Incorporating animal manure fertilizers helps prevent their movement in the landscape. Avoid applying fertilizer materials too near to surface water bodies. Proper application timing The timing of fertilizer applications is important because the nutrients’ availability to the plants decrease over time. Nitrogen is especially efficient when it is applied close to the time of crop up take. Applying N too early increases the probability it will leave the field, and supplemental N fertilizer may be necessary later in the growing season. Fall application of N is not practical in Mississippi for crops seeded in the spring, whether the fertilizer is organic or inorganic. Recent Mississippi research has confirmed that the N in poultry litter is much less efficient for row crops when the litter is applied in the fall. Inorganic P fertilizers may be applied in the fall before a spring-seeded crop, as phosphorus is not mobile in the soil. However, P fixation in soils is common, so P is not very efficient no matter when it is applied. In contrast to P fertilizers, K fertilizer effectiveness is not affected by soil fixation except in some high clay content soils. Inorganic potash fertilizers for spring crops may be field applied in the fall if the soil Cation Exchange Capacity (CEC) is 8 or higher; it may be lost via leaching at lower CEC values. Equipment maintenance and calibration Equipment maintenance and calibration are key to efficient nutrient applications. Know the correct application width for the equipment and the material being applied; avoid overlaps within the field and onto field borders. Ensure that belts and chains are properly maintained and adjusted. equipment. Precision technology Precision technologies may allow more efficient fertilizer management of nutrient deficient, acidic, or more responsive soil areas. However, these tools, which can include management software, special equipment, consultants, soil maps, and training, may be very expensive. Sumber: ….. Diunduh 17/3/2012http://msucares.com/pubs/publications/p2647.pdf#page=27

111 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Meminimumkan potensi transpor hara dari lahan ke perairan Conservation tillage Some nutrients, such as P ions, are closely bound to soil particles, so soil management that minimizes erosion also minimizes movement of those nutrients. These management practices include strip-tillage, mulch tillage, no-tillage, or ridge-tillage. Proper storage of animal by-products Proper storage of poultry litter is important. Many poultry growers have dry stack sheds to store litter, but farmers acquiring litter may need to store it temporarily. Recent research by Auburn University found that litter should be covered with plastic or other materials to protect its nutrient content. Control water flow on and off fields Controlling water flow with surface and subsurface drainage management reduces nutrient, pathogen, and pesticide runoff into downstream waters. Proper water control also reduces wind erosion and dust and may provide seasonal wildlife habitat. Maintain buffers Planted buffers between nutrient applications and nearby water bodies reduce sheet and rill erosion and lower the rate of sediment delivery. Planted buffers may use nutrients that move from planted areas and would otherwise enter surface waters. As with other BMP’s, contact local agency offices or groups such as Delta F.A.R.M. for more detailed information on buffer installation and cost-share programs. Sumber: ….. Diunduh 17/3/2012http://msucares.com/pubs/publications/p2647.pdf#page=27

112 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Minimize the potential transport of nutrients from fields to water bodies 1.Conservation tillage Some nutrients, such as P ions, are closely bound to soil particles, so soil management that minimizes erosion also minimizes movement of those nutrients. These management practices include strip-tillage, mulch tillage, no-tillage, or ridge-tillage. 2.Proper storage of animal by-products Proper storage of poultry litter is important. Many poultry growers have dry stack sheds to store litter, but farmers acquiring litter may need to store it temporarily. Recent research by Auburn University found that litter should be covered with plastic or other materials to protect its nutrient content. 3.Control water flow on and off fields Controlling water flow with surface and subsurface drainage management reduces nutrient, pathogen, and pesticide runoff into downstream waters. Proper water control also reduces wind erosion and dust and may provide seasonal wildlife habitat. 4.Maintain buffers Planted buffers between nutrient applications and nearby water bodies reduce sheet and rill erosion and lower the rate of sediment delivery. Planted buffers may use nutrients that move from planted areas and would otherwise enter surface waters. Sumber: ….. Diunduh 17/3/2012http://msucares.com/pubs/publications/p2647.pdf#page=27

113 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Mississippi State University Extension Service Soil Testing-Based Recommendations for Hay and Pasture Crops Sumber: ….. Diunduh 17/3/2012http://msucares.com/pubs/publications/p2647.pdf#page=27

114 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Mississippi State University Extension Service Soil Testing-Based Recommendations for Annual Agronomic Crops Sumber: ….. Diunduh 17/3/2012http://msucares.com/pubs/publications/p2647.pdf#page=27

115 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Mississippi State University Extension Service Soil Testing-Based Recommendations for Annual Agronomic Crops Sumber: ….. Diunduh 17/3/2012http://msucares.com/pubs/publications/p2647.pdf#page=27

116 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Mississippi State University Extension Service Soil Testing-Based Recommendations for Annual Agronomic Crops Sumber: ….. Diunduh 17/3/2012http://msucares.com/pubs/publications/p2647.pdf#page=27

117 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Mississippi State University Extension Service Soil Testing-Based Recommendations for Annual Agronomic Crops Sumber: ….. Diunduh 17/3/2012http://msucares.com/pubs/publications/p2647.pdf#page=27

118 Nutrient Management Guidelines for Agronomic Crops Grown in Mississippi Larry Oldham, Ph.D. Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State University Mississippi State University Extension Service Soil Testing-Based Recommendations for Annual Agronomic Crops Sumber: ….. Diunduh 17/3/2012http://msucares.com/pubs/publications/p2647.pdf#page=27

119 Quality Water for Idaho Current Information Series No. 962 Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler Nitrogen Best Management Practices for the Protection of Groundwater Apply nitrogen at recommended rates for crop production. Use preplant soil profile nitrate testing and soil and plant nitrate testing when appropriate during the growin season. Base nitrogen application rates on realistic yield goals. Credit nitrogen contributions from legumes, manures, and other organic wastes. Plan nitrogen applications to correspond with crop demand and availability to the crop. Do not apply nitrogen fertilizer in the fall on coarse textured soils, on shallow soil over fractured bedrock, or on soils with a water table close to the soil surface. Use nitrification inhibitors when soil conditions and nitrogen application timing may promote leaching. Uniformly apply manure across a field in accordance with crop nutrient requirements. Schedule irrigation to minimize leaching. Manage fertigation systems carefully. Diversify crop rotations to include crops that utilize deep residual nitrogen. Sumber: ….. Diunduh 17/3/2012

120 Quality Water for Idaho Current Information Series No. 962 Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler. Nitrogen is an element essential for all plant and animal life. The interlocking succession of nitrogen reactions occurring in the soil is known as the nitrogen cycle (fig. 1). Agriculture affects both nitrogen additions and subtractions to the soil. Additions include nitrogen fertilizers, crop residues, nitrogen fixation by legumes, and manures. Subtractions attributed to agriculture include crop removal (harvesting), plant uptake, and nitrogen leaching. Sumber: ….. Diunduh 17/3/2012.

121 Quality Water for Idaho Current Information Series No. 962 Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler Specific types of BMPs for nitrogen fertilizer management that should be employed in many areas of Idaho include: 1.Pengambilan contoh tanah 2.Rekomendasi pupuk berdasatkah hasil riset 3.Waktu aplikasi pupuk 4.Lokasi penempatan pupuk di tanah 5.Kredit hara untuk legumes dan pupuk kandang 6.Penghambat Nitrifikasi 7.Pengelolaan rabuk kandang 8.Pengelolaan sistem irigasi 9.Pupuk N lambat tersedia 10.Pemilihan pola rotasi tanaman 11.Pengelolaan pupuk yang beragam. Sumber: ….. Diunduh 17/3/2012

122 Quality Water for Idaho Current Information Series No. 962 Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler Soil Sampling Soil sampling is an important BMP that considers the amount of plant available nitrogen already in the soil profile. Soil sampling should be done 3 to 4 weeks before planting a crop. The soil samples should be representative of the field. Normal sampling depth is to 12 inches for phosphorus, potassium, sulfur, and micronutrients. Soil samples for nitrogen should be collected to the effective crop rooting depth. Information on soil sampling details can be found in University of Idaho Extension Bulletin 704, Soil Sampling. The need frequency of soil tests for a nutrient depends on such things as its mobility in the soil and the nutrient requirement of the crop to be grown. Soil samples for determination of phosphorus, potassium, and micronutrients should be taken at least once during each crop rotation cycle. For best soil fertility management, especially for mobile nutrients such as nitrogen and sulfur, soil testing should be done each year, and crops should be fertilized for a realistic crop yield goal. Having an analysis performed for every nutrient each year is not necessary. A record of soil test results should be maintained on each field to evaluate long-term trends of nutrient levels. Sumber: ….. Diunduh 17/3/2012

123 Quality Water for Idaho Current Information Series No. 962 Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler Fertilizer Recommendations Based on Research Nitrogen application rates for crops should be based on scientific information. Reliable fertilizer recommendations are developed by calibrating and correlating laboratory soil test values with field plot research on crop response to fertilizer rates. The University of Idaho has developed more than 30 fertilizer guides for crops. The data base used to develop these fertilizer guides is extensive and has been collected for over three decades. Fertilizer guides take into account the amount of residual nitrogen in the soil profile, the amount of nitrogen mineralized (released) from organic matter decomposition during the growing season, crop yield potential, and plant residue from the previous crop. Sumber: ….. Diunduh 17/3/2012

124 Quality Water for Idaho Current Information Series No. 962 Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler WAKTU APLIKASI PUPUK The timing of nitrogen fertilizer applications is an important factor affecting crop yield, efficiency of nitrogen use, and a grower's economic return. The period between nitrogen application and actual crop uptake is critical. This is when high concentrations of nitrogen as nitrate can be lost through leaching. Groundwater quality is especially vulnerable where the water table is close to the soil surface. Some BMPs for timing of fertilizer applications include: (1)applying nitrogen to a cool season crop in the spring instead of the previous fall, (2)applying only a portion of the needed nitrogen as a preplant treatment, (3)using split or multiple nitrogen applications where appropriate, (4)using side-dressed or top-dressed applications during the growing season if irrigated or adequate precipitation is expected to move it into the root zone, and (5)using a combination of tissue analysis for diagnosis and topdressed nitrogen applications during the growing season. Sumber: ….. Diunduh 17/3/2012

125 Quality Water for Idaho Current Information Series No. 962 Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler LOKASI PENEMPATAN PUPUK Placement of fertilizers is an integral part of efficient crop management. Correct placement of fertilizers often improves the efficiency by which nutrients are taken up by plants and consequently encourages maximum yields of intensively managed agronomic crops. Correct fertilizer placement is more critical for maximum crop yields under reduced tillage systems than with conventional tillage management. Some BMPs for fertilizer placement include: (1)applying nitrogen below the seed at planting, (2)applying a small portion of the nitrogen pop-up (with the seed) at planting, (3)banding nitrogen on the soil surface where leaching is a potential problem, and (4)spring topdressed nitrogen applications where soil test, plant tissue test, or environmental concerns warrant it. Sumber: ….. Diunduh 17/3/2012

126 Quality Water for Idaho Current Information Series No. 962 Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler Kredit Hara untuk Legumes dan Pupuk Kandang Effective use of nitrogen fertilizer requires consideration of nitrogen supplied in manure applications and by legume crops in the rotation. Observations in other areas have shown that manures can supply crop nutrients effectively and may often meet the total nitrogen needs of the planted crop. In addition, a good clover or alfalfa stand may provide up to 200 pounds of nitrogen for subsequent crops in the rotation. Crediting nitrogen supplied from manures and legumes against crop nitrogen needs can substantially reduce nitrogen fertilizer application rates and the potential for overapplication of nitrogen. Penghambat Nitrifikasi Nitrification inhibitors prevent the conversion of relatively immobile ammonium-based nitrogen fertilizers to very mobile nitrate in agricultural soils. Research has shown nitrification inhibitors are most effective where nitrogen fertilizer is applied in the fall or early spring. Sumber: ….. Diunduh 17/3/2012

127 Quality Water for Idaho Current Information Series No. 962 Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler PENGELOLAAN PUPUK KANDANG Manure is often viewed as a waste product for disposal rather than as a resource for supplying nutrients to the soil. Manure can supply sufficient quantities of nutrients to crops, add organic matter to soils, improve soil structure and tilth, and improve the soil's water holding capacity. PENGELOLAAN SISTEM IRIGASI More than 50 percent of Idaho's cropland is under irrigation. In many areas of Idaho the water table is shallow, which makes irrigation management crucial. There is substantial evidence that excessive applications of irrigation water may be the primary factor in increasing nitrate levels in groundwater in southwestern and southcentral Idaho, and on the Fort Hall Indian Reservation in southeastern Idaho. An irrigaion manager should consider the following to protect groundwater: (1) irrigation scheduling to minimize leaching, (2) credits for nitrate in irrigation water, and (3) adequate precautions when practicing fertigation and chemigation. Sound nitrogen management alone will not prevent groundwater contamination under irrigated conditions. Even with the most accurate nitrogen application, overirrigation can cause nitrate to move below the crop rooting zone. Consequently, best management practices for proper irrigation scheduling need to be included. A sound irrigation management program considers soil water-holding capacity, crop growth stage and anticipated water use, evaporation rate, rainfall, and previous irrigation to determine the timing and amount of irrigation water to be applied. Sumber: ….. Diunduh 17/3/2012

128 Quality Water for Idaho Current Information Series No. 962 Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler PUPUK NITROGEN LAMBAT TERSEDIA (Slow-Release ) At present, the use of slow-release fertilizers is not economical for most crops grown in Idaho. This is because slow-release materials usually cost 30 to 40 percent more per pound of nitrogen than conventional nitrogen fertilizers. However, slow-release materials often improve nitrogen use efficiency in crops by up to 30 percent. PERGILIRAN TANAMAN The selection of crops in a rotation has an influence on the movement of nitrogen through soils. Legumes and other crops that do not require large additions of nitrogen fertilizers can often utilize or scavenge nitrogen remaining in the soil from the previous crop. In addition, rotating crops with low nitrogen fertilizer requirements in sequence with crops that require high nitrogen inputs or crops that inefficiently recover nitrogen can reduce the amount of nitrogen applied. PEMUPUKAN Variable fertility management within a single field is a strategy that can potentially improve nutrient use efficiency, improve economic crop returns, and reduce environmental pollution. A variable fertilizer management strategy can be easily tailored for any field. Basically the only knowledge a grower needs to implement this type of BMP is how yield varies across a field. Differences in soil color, landscape position (slope, elevation, aspect, etc.), and in the appearance of crops or soil may also help to delineate fertility management units. A variable management strategy follows these steps: (1) the field is divided into different fertility management units based primarily on yield potential, (2) separate sets of soil samples and separate soil tests are made on each management unit in the field, (3) nitrogen fertilizer is applied based on soil test results and yield potential using fertilizer guides for each management unit, and (4) phosphorus, potassium, and sulfur are applied based on soil sampling and analysis from each management unit. Sumber: ….. Diunduh 17/3/2012

129 COLORADO STATE UNIVERSITY EXTENSION Bulletin #XCM-175 Reagan M. Waskom and Troy Bauder Best Management Practices PEMUPUKAN FOSFAT Phosphorus (P) is an essential nutrient for all forms of terrestrial life and is one of the 18 chemical elements known to be required for plant growth. In Colorado, agricultural soils generally contain from 800 to 2,000 pounds of total P per acre in the tillage layer. However, most of it is in insoluble compounds unavailable to plants. The remainder cycles within plants, animals, soil, and the soil solution in biologically available forms and organic P compounds. A simplified P cycle showing the principal P inputs and sinks. In production agriculture, fertilizer and manure are the major P additions to this cycle. Without these inputs, intensive commercial agriculture would not be viable on many soils. However, proper management of soils and P fertilizers is essential to protect water quality from degradation. Water quality problems associated with phosphorus are generally confined to surface water. Phosphorus in most Colorado soils is tightly held to soil particles and does not leach. However, the P held in organic phases from residues such as manure can dissolve in water and be lost if improperly managed. Adsorbed P on soil particles can cause surface water contamination as P containing sediments move off the land in agricultural runoff. When large amounts of nutrients enter lakes and streams, they accelerate the natural aging process, or eutrophication, by enhancing the growth of algae and other aquatic weeds. As these plants flourish, depleted oxygen and light reduce the survival of more desirable species and the natural food chain declines. Eventually, impounded waters such as lakes, ponds, and reservoirs become overgrown with aquatic vegetation and, in a sense, die. Sumber: ….. Diunduh 17/3/2012

130 Phosphorus in Agricultural Soils When added to soil, P fertilizer undergoes several different reactions, including adsorption on soil particles and precipitation. A number of factors determine the speed and fate of the reactions. They include soil pH, moisture and texture, chemical properties of the soil, and form of fertilizer used. The net result in most Colorado soils is fixation of P by calcium in relatively insoluble and unavailable forms. For this reason, recommendations for soils low in available P often exceed actual crop removal (Table 1). Table 1. Phosphorus removed in harvested crops Sumber: Diunduh 17/3/2012 COLORADO STATE UNIVERSITY EXTENSION Bulletin #XCM-175 Reagan M. Waskom and Troy Bauder Crop Yield P removed (per acre) (lb P2O5/A) Alfalfa 4 tons 40 Corn (grain) 190 bu 70 Corn (silage) 30 tons 120 Barley 100 bu 40 Bromegrass/fescue 4 tons 40 Potatoes 400 cwt 55 Sugarbeets 25 tons 35 Sunflowers 2,000 lb 80 Wheat 100 bu 85 Source: Adapted from BMP for Manure Utilization 568A

131 PENGELOLAAN PUPUK UNTUK MEMIIMUMKAN KEHILANGAN P DAN MEMAKSIMUMKAN KEUNTUNGAN Applying P fertilizer at rates higher than production requirements is unwise from both environmental and economic viewpoints. Today, there is no agronomic justification for building P soil test levels higher than crop sufficiency levels. Phosphorus losses in surface runoff have been shown to increase with increased P application rates. Therefore, once the crop sufficiency levels have been reached in your fields, P applications should be made only as dictated by soil testing. Placement of P fertilizer will influence the amount of P available for transport to surface water. Correct placement of fertilizers in the plant root zone will improve fertilizer use efficiency and seedling vigor, and reduce the amount of P in agricultural runoff. Phosphorus fertilizer should not be broadcast on the soil surface without incorporation, except on perennial forages. In established alfalfa stands, P fertilizer normally should not be applied in the late fall or winter when growth is minimal and runoff potential is high. Broadcast applications generally are less efficient and leave more P at the soil surface than banding. Band application at planting is considered the most efficient method for many crops. Subsurface placement is especially important under reduced tillage cropping systems to achieve maximum crop yields. Variable fertilizer rate management can improve both fertilizer use efficiency and economic returns. While this strategy can be adopted for any fertilized field, it makes the most sense in relatively large fields where the producer has knowledge of how crop yields and soil type vary across the field. To use a variable fertilizer rate strategy: 1.Divide the field into different management units based upon a map of yields or soil types. 2.Soil sample the management units separately. 3.Fertilize each unit according to P soil test level and yield capability. Field maps should be modified at harvest as necessary to refine the boundaries of management units. Consult with your fertilizer dealer or crop advisor prior to adopting this BMP. Sumber: Diunduh 17/3/2012 COLORADO STATE UNIVERSITY EXTENSION Bulletin #XCM-175 Reagan M. Waskom and Troy Bauder

132 PENGELOLAAN PUPUK KANDANG UNT MEREDUKSI KEHILANGAN P Manure is an excellent source of P for crop production. However, if manure is not incorporated into the soil, runoff may carry both soluble and sediment-associated nutrients to surface waters. The most common strategies for manure utilization are (1) application for maximum nutrient efficiency and (2) application for maximum disposal rates of manure. While the second strategy presents a more difficult challenge from a water quality viewpoint, both management methods should consider application rates, timing, site characteristics, and water quality impacts. Manure managed for maximum nutrient efficiency is the most sound manure application program. Producers need soil and manure analyses to determine the correct application rate based upon crop uptake of N and P. Either of these nutrients may limit application rate, as both nutrients are present in large quantities in manures. In many cases, the best program is to rotate fields receiving manures to avoid salt or nutrient buildup. The farmer/ producers faced with the need for manure disposal at maximum application rates should have manures analyzed for nutrient content and apply according to crop nitrogen needs. However, this strategy may lead to an accumulation of P over long-term, repeated applications. Therefore, it is essential that producers manage water on their field carefully, minimizing runoff and leaching. Poultry manure contains exceptionally high levels of P and should be applied at rates based upon crop P removal. Annual soil tests are strongly recommended on all fields receiving manure. Operators should rotate manure applications when soil tests show nutrient levels greater than, or sufficient for, crop needs. Sumber: Diunduh 17/3/2012 COLORADO STATE UNIVERSITY EXTENSION Bulletin #XCM-175 Reagan M. Waskom and Troy Bauder

133 The Colorado Phosphorus Risk Assessment (COPI) is an evaluation tool to estimate P loss from manured fields. Fields that receive frequent high rates of manure should be evaluated using the COPI to determine risk of P loss and management changes that could lower this risk. As with commercial P fertilizers, manure should be incorporated immediately after application. Injection of liquid manure beneath the soil surface with specialized equipment is also a recommended practice. Unlike commercial fertilizer, the P content of manure can vary significantly. Approximate values are available for various manure sources, but manure sampling and analysis are the best way to calculate nutrient credit. Table 2. Approximate P content of various manures1 when applied to land (wet weight basis) Sumber: Diunduh 17/3/2012 COLORADO STATE UNIVERSITY EXTENSION Bulletin #XCM-175 Reagan M. Waskom and Troy Bauder

134 PENGELOLAAN TANAH UNTUK MEREDUKSI KEHILANGAN P Although there are a number of sources of sediment entering our waters, soil erosion from agricultural fields is a significant contributor to nonpoint source pollution. The consequences of cropland erosion include loss of fertile topsoil, eutrophication and sedimentation of surface waters, destruction of habitat, and decreased recreational and aesthetic value of lakes and streams. Runoff from agricultural land also can transport pesticides and microbial pathogens, as well as nutrients. Owners of agricultural land should contact the Natural Resources Conservation Service (NRCS) for help in evaluating the erosion potential of their lands and in determining what control measures are needed. In some cases, the NRCS has cost-share funds available to help producers install BMPs on their land. A number of management practices and structures for controlling runoff and erosion are currently available for use. In some cases, there is a trade-off between reducing runoff and increasing deep percolation to groundwater. BMPs for managing surface runoff and soil erosion are listed. Sumber: Diunduh 17/3/2012 COLORADO STATE UNIVERSITY EXTENSION Bulletin #XCM-175 Reagan M. Waskom and Troy Bauder

135 Table 3. Erosion control BMPs for reducing surface losses of phosphorus from crop fields Sumber: Diunduh 17/3/2012 COLORADO STATE UNIVERSITY EXTENSION Bulletin #XCM-175 Reagan M. Waskom and Troy Bauder

136 Phosphorus BMPs 1.Sample the tillage layer of soil in each field on a regular basis and have soil analyzed to determine available soil P levels prior to applying P fertilizer. 2.Credit all available P from manures and other organic residues to the P requirement for the crop. 3.Fertilize soils with ‘low’ to ‘medium’ P soil test values using environmentally and economically sound agronomic guidelines. In general, soils testing ‘high’ will not respond to additional P and should not receive fertilizer unless a banded starter is needed to compensate for low soil temperatures. Phosphorus fertilizer should not be applied to soils testing ‘very high’ for soil P. 4.Divide large, non-uniform fields into smaller fertility management units based upon yield potential or soil type and fertilize according to P levels determined through soil analysis. 5.Apply P fertilizers where they can be most efficiently taken up by the crop. Band application of P in the root zone reduces surface loss potential and enhances nutrient availability, especially in cold or P deficient soils. 6.Incorporate surface applied P into the soil where any potential for surface runoff or erosion exists. 7.Minimize soil erosion and corresponding P losses by establishing permanent vegetative cover, conservation tillage and residue management, contour farming, strip cropping, and other management practices as feasible. When erosion potential is severe, install structures such as diversions, terraces, grass waterways, filter fences, and sediment basins. Contact your local NRCS office if you need assistance in evaluating erosion potential and control options. 8.Maintain a buffer strip (where fertilizer and manure is not applied) a safe distance from surface water and drainage channels. 9.Maintain grass filter strips on the downhill perimeter of erosive crop fields to catch and filter P in surface runoff. 10.Manage irrigation water to minimize runoff and erosion by meeting the Irrigation BMPs or the NRCS approved Irrigation Water Management practice standard and specification. 11.Evaluate fields with historical manure applications using the Colorado Phosphorus Index Risk Assessment. Sumber: Diunduh 17/3/2012 COLORADO STATE UNIVERSITY EXTENSION Bulletin #XCM-175 Reagan M. Waskom and Troy Bauder

137 The phosphorus cycle in agricultural soils. Sumber: Diunduh 17/3/2012 COLORADO STATE UNIVERSITY EXTENSION Bulletin #XCM-175 Reagan M. Waskom and Troy Bauder Phosphorus placement influences the amount available for transport. Band placement of P fertilizers is recommended for erosive soils.

138 All organic matter in soil is not equal Scientists describe 3 pools of soil organic matter Passive SOM 500 – 5000 yrs C/N ratio 7 – 10 Active SOM 1 – 2 yrs C/N ratio 15 – 30 Slow SOM 15 – 100 yrs C/N ratio 10 – 25 Recently deposited organic material Rapid decomposition 10 – 20% of SOM Intermediate age organic material Slow decomposition 10 – 20% of SOM Very stable organic material Extremely slow decomposition 60 – 80% of SOM CO 2

139 PENGELOLAAN BAHAN ORGANIK TANAH But not all soil organic matter is equal. It is a long, slow process to convert fresh residues or manure into stable soil humus, and scientists have discovered there are different categories of organic matter. The active pool of organic matter is the freshest organic material, plant and animal residues that have just begun to decompose. This is the pool that gives the largest release of nutrients, where decomposition is most rapid and the largest amount of carbon dioxide is released back into the atmosphere. Decomposition of this pool also has the greatest effects on soil structure formation and stabilization. Thus many of the benefits of SOM are from this active or fresh pool – nutrient supply, improved structure, improved water infiltration, decreased erosion, stimulated microbial activity. This is the most dynamic part of the soil organic matter, the pool that undergoes the greatest change and turnover. At the other end of the line is the largest pool of soil organic matter, often called the passive pool. This organic matter is very stable. It has gone through many cycles of decomposition and the molecules that are left here are so complex that microbes have a hard time biting into them or using them as food energy. Scientists have been able to determine that some of this organic matter has been in the soil for as long as 5000 years. The passive organic matter is largely responsible for the increased cation exchange capacity and water holding capacity in soil. In between the active and passive pools of organic matter is the so called slow organic matter. In reality there are not three distinct pools, but rather a continuum of organic materials that ranges from active to passive. The slow organic matter pool has properties that are intermediate between active and passive. It also contributes to cation exchange capacity and water holding capacity. Sumber: ….. Diunduh 17/3/2012

140 Decomposition (CO 2 ) Erosion If inputs increase and losses remain the same, SOM will increase Soil Organic Matter Losses Inputs Crop Residues Crop Roots Manure Compost Conversely, if inputs are increased and losses remain constant, SOM levels will increase. Ideally, if we want to increase SOM levels we need to not only increase the inputs, but also decrease the losses. So lets start thinking about how we can do that in a crop production system.

141 SOM will not continue to increase or decrease indefinitely When inputs or losses are changed, SOM quantity changes to a different level and a new steady state condition is reached. SOM level Years of cultivation SOM in virgin soil Steady state SOM after years of continuous corn cultivation New steady state SOM level Management change imposed Corn-oats-clover rotation plus manure application Several long-term studies of soil organic matter levels in production agriculture fields have found that a relatively rapid decrease in SOM occurs during the first 15 – 20 years of cultivation and then the rate of loss slows and reaches a steady state level much lower than in the original soil.

142 DINAMIKA BAHAN ORGANIK TANAH Kecepatan dekomposisi BOT dipengaruhi oleh: 1. Environmental Conditions Temperature Moisture Aeration (oxygen) Soil texture Soil pH Soil fertility 2. Quality of added Organic Material C/N ratio Composition/Age Physical properties and placement Fresh vs. “processed” Which of these factors can you control?? Some factors influence the rate of loss of organic material from soil. These can be divided into Soil Environmental factors and factors related to the Quality of the organic material being added to the soil. We have already discussed the influence of C/N ratios and the composition of plant material. The age at which cover crops are killed and possibly turned under can have a big impact on how quickly they decompose. Fresh, green material will break down much faster than mature, dry material. Physical properties, mainly the size of pieces has a big impact. Compare how long it takes a tree limb to decompose if it lays intact on the soil surface compared to if it is shredded or reduced to sawdust. Compare the difference in decomposition of straw on the soil surface versus straw that has been incorporated by tillage. Some organic materials applied to soils have already undergone some decomposition – these are materials such as composts, manures, and biosolids. Such materials are already similar in many ways to the active soil organic matter pool and their rate of decomposition is slower than fresh material. When it comes to environmental conditions, anything that influences microbial activity in soil will influence decomposition rates. Microbes like to be comfortable. They prefer warm, but not too hot temperatures, sufficient moisture, but not too much. And they love oxygen. Decomposition can happen anaerobically (without oxygen) but it is much slower than aerobic decomposition. In general, conditions that favor good crop growth will also favor decomposition. Also pH ranges and soil fertility levels that favor good crop production will also favor decomposition. Generally coarse textured, sandy soils have less organic matter than heavier, fine textured soils with a lot of clay. This is because sandy soils tend to be better aerated and there is less physical protection of organic matter within soil aggregates.

143 Distribution of organic matter in soil under conventional and no tillage No-till Conventional Tillage One major difference between conventional tillage and no-till systems is in how the soil organic matter is distributed in the profile. In CT systems, crop residues and roots get mixed uniformly through the plow layer so there is very little change in SOM in the upper 15 to 20 cm. In NT systems, crop residues and manures are left on the soil surface and only mixed by worms and other soil macroarthropods. This means that most added organic materials decay near the soil surface and consequently SOM concentrations are greatest at the surface and decrease with depth. There is actually very little difference between the two systems deeper in the profile. Again, most of these increases are in the active SOM pool. This is the pool with highest rates of decomposition and turnover of material. But since this is the pool that has the greatest influence on soil aggregation and stability and water infiltration and ease of root extension, it is actually desirable to have this large active pool located near the soil surface.

144 PENGELOLAAN UNTUK MEMPERBAIKI BOT Soil Organic Matter is dynamic. The amount of SOM depends on the balance between inputs of organic material and losses of SOM from decomposition and erosion. Both the quantity and quality of organic material inputs can be managed to increase SOM levels. Losses of SOM can be reduced by decreasing erosion and decreasing tillage. Most change in SOM occurs in the active SOM pool. Many soil quality benefits accrue from the active pool. Maintaining the size and rapid turnover in the active pool may be more important for soil quality than actually increasing the overall SOM level. Key points to remember about SOM are: 1.Unlike the static mineral fraction of soil, SOM is dynamic and undergoes constant change and turnover. 2.SOM can be thought of as a reservoir. The level of SOM in the reservoir depends on the rate of additions and the rate of removals. 3.On the input side, SOM can be increased by increasing the quantity of organic material added to soil. SOM can also be increased by adjusting the quality of added organic materials to include some that decompose more slowly. 4.Losses of SOM can be decreased by taking measures to reduce erosion and even more significantly by reducing tillage. 5.Losses and gains of SOM over short time periods (5 – 10 years) occur mostly in the active SOM pool with almost no change in the passive SOM pool. 6.Many of the soil quality benefits attributed to SOM are due to activity in the active SOM pool. 7.For this reason, to obtain the soil quality benefits of SOM maintaining the size of the active SOM pool and a rapid turnover of carbon in this pool may be more important than achieving substantial increases in overall SOM levels.


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