Presentation on theme: "Jurs Tanah FP-UB --- PSLP PPSUB"— Presentation transcript:
1Jurs Tanah FP-UB --- PSLP PPSUB KOMPENDIUMKAJIAN LINGKUNGANPENGELOLAANKESUBURAN TANAHDikoleksi oleh :Prof.Dr.Ir.Soemarno,M.S.Jurs Tanah FP-UB PSLP PPSUBSeptember 2011
2Bahan induk, Iklim, Relief, Organisme, atau Waktu. KESUBURAN TANAHKesuburan 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
3Ciri-ciri Tanah Subur: Kaya unsur hara esensial yang tersedia untuk pertumbuhan tanaman, termasuk nitrogen, phosphorus dan kalium.It contains sufficient minerals (trace elements) for plant nutrition, including boron, chlorine, cobalt, copper, iron, manganese, magnesium, molybdenum, sulfur, and zinc.It contains soil organic matter that improves soil structure and soil moisture retention.Soil pH is in the range 6.0 to 6.8 for most plants but some prefer acid or alkaline conditions.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.Beraneka-ragam mikroba tanah mendukung pertumbuhan tanaman.Topsoilnya cukup tebal.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 SuburSumber: ….. Diunduh 15/3/2012
4SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.Lack of soil fertility causes decreased yields but manyplant 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.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.Sumber: journeytoforever.org/farm_library/AD2.pdf….. Diunduh 15/3/2012
5SOIL FERTILITY MANAGEMENT Crop husbandry measures Laura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.Crop husbandry measuresCrop husbandry measures refer to methods the farmer can use before,during and after the growing season that do not require the addition ofa new component to his business nor the purchase of many extra inputs(just sowing or planting materials). These measures includemulching, green manuring, intercropping, green fallow periods, andagroforestry.All of the above methods are intended to achieve and retain optimumconditions in the root zone, where the crop gets the nutrients andmoisture it needs for good production. Also the soil must be penetrablefor 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.Sumber: journeytoforever.org/farm_library/AD2.pdf….. Diunduh 15/3/2012
6SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.BAHAN ORGANIK TANAHOrganic 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.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.Sumber: journeytoforever.org/farm_library/AD2.pdf….. Diunduh 15/3/2012
7SOIL FERTILITY MANAGEMENT Laura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.BAHAN ORGANIK TANAHCrop 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.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 TANAHSumber: journeytoforever.org/farm_library/AD2.pdf….. Diunduh 15/3/2012
8SOIL FERTILITY MANAGEMENT Soil fertility and fertilisers Laura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.Soil fertility and fertilisersThe 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.Pada tanah-tanah yang miskin bahan organik, aplikasi pupuk kimia buatan harus dibarengi dengan aplikasi bahan organik secukupnyaSumber: ….. Diunduh 15/3/2012
9KESUBURAN 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:mulching is a method, in which a layer fresh organic matter is placed on top of the soil;green manuring consists in ploughing under fresh green material;intercropping means growing two or more crops together on the same field;during green fallow periods, species are sown or stimulated that have better qualities then the species that would grow spontaneously in the fallow period;agroforestry comprises all forms of land use in which woody species (trees and shrubs) are grown in combination with other crops.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)INTERCROPPINGSumber: journeytoforever.org/farm_library/AD2.pdf….. Diunduh 15/3/2012
10Husbandry means managing resources or caring for animals and crops: CROP HUSBANDRY SYSTEMHusbandry means managing resources or caring for animals and crops:Thrifty management of a household is an example of husbandry.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: )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 HUSBANDRYSumber: lada.virtualcentre.org/.../download.asp?pub….. Diunduh 18/3/2012
11Better Land Husbandry Components The intrinsic components to Better Land Husbandry (BLH):Promotion of an integrated and synergistic resource management approach embracing locally appropriate combinations of the following technical options: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); andreclamation, 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.Sumber: lada.virtualcentre.org/.../download.asp?pub….. Diunduh 18/3/2012
12College of Agricultural Sciences PENN STATE EXTENSION.College of Agricultural SciencesAGRONOMY GUIDE. CROP AND SOIL MANAGEMENT. Section II. Soil Fertility ManagementThe 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.Uji Tanah dan TanamanSumber: Diunduh 15/3/2012
13All inputs are managed, using sound agronomic principles. 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.ISFM interventions have been developed formaize, sorghum, and cassava-based systemsin the major impact zones. Yield increaseswere over 100%, even as soil fertility statusimproved. Activities are now directed towardsachieving the same successes with riceandbanana-based systems. Conservationagricultural practices are also being developed.Sumber: Diunduh 15/3/2012
14PENGELOLAAN KESUBURAN TANAH Goals of a Sustainable Soil Fertility Management Program1. To sustain high crop productivity and crop quality in food and fiber productiona) Crop productivity, crop quality, and the success of a given operation2. To minimize risks to environmental quality and human health associated with agricultural productionImportant steps in minimizing human health risks, and on and off-farm impactsAvoid the use of all synthetically compounded materials; balance inputs of organic matter and mineral inputs to avoid exceeding crop needsAvoid creating nonpoint source pollution through surface runoff and leachingPrevent soil erosion and sedimentation of waterwaysClose nutrient cycles as much as possible within the field and farmClose nutrient cycles at multiple scales: watershed, regional and national scalesSumber: Diunduh 15/3/2012
15Components of a Sustainable Soil Fertility Management Program 1. Improve and maintain physical and biological properties of soila) Sustainable agricultural practices used to improve and sustain soil physical and biological propertiesMaintaining or building soil organic matter (SOM) levels through inputs of compost and cover croppingProperly timed tillageIrrigationSound 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.Integrated plant nutrient components in the Nepalese farming systemSumber: Diunduh 15/3/2012
16Components of a Sustainable Soil Fertility Management Program 2. Improve and maintain chemical properties of soila) Benchmarks of optimal soil chemistryBalanced levels of available plant nutrients (see Unit 1.11, Reading and Interpreting Soil Test Reports)Soil pH ~6.0–7.0Low salinity levelsb) Sustainable agricultural practices used to develop and maintain optimal soil chemical propertiesProvide a balanced nutrient supply for the cropConduct soil sampling and periodic monitoringConduct plant tissue testingTime 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 moistureAvoid leaving fields bare to avoid wind and water erosion and nutrient leachingManage irrigation carefully to avoid runoff, erosion, and leaching of soluble nutrientsSupply major nutrients primarily through organic matter and mineral soil amendmentsAllow sufficient time for fresh residue to break down before planting cropsUse in-season supplemental fertilizers when necessarySumber: Diunduh 15/3/2012
17Components of a Sustainable Soil Fertility Management Program 3. Minimize disease/pest susceptibilitya) Sustainable agriculture practices used to minimize disease/pest susceptibility in organic farming systemsMaintain soil nutrient levels and soil pH within optimal rangeBuild and maintain soil organic matter to promote desirable soil physicalproperties and supply essential plant nutrientsMaintain soil moisture within optimal ranges for plant growth and the avoidance of compaction and erosionDesign appropriate rotations to break pest cyclesPlant polyculturesUse appropriate preventative and active biocontrol practicesPolyculture 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)Sumber: Diunduh 15/3/2012
18Soil Fertility and Soil Quality in Sustainable Farming Systems KESUBURAN TANAH DAN KUALITAS TANAHKualitas TanahIndikator Kualitas TanahKetersediaan haraKetersediaan airPromotes good root growth and maintains good habitat for soil organismsMencegah degradasiMaintains good soil structure to provide adequate aeration and tilthGood soil structure allows for rapid water infiltrationpH moderat (6.0–7.5)Tingkat salinitas rendahLow levels of potentially toxic elementsKesuburan tanah berimbang.c) Soil fertility: The capacity of a soil to provide nutrients required by plants for growth; one component of soil quality2. Soil fertility, plant health, and the resistance and resilience of crop plants to pest and pathogensConcept of Nutrient AvailabilitySoil 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 asMass flowCation exchange and anion exchangeDiffusionSumber: Diunduh 15/3/2012
19PENGELOLAAN KESUBURAN TANAH PENGOLAHAN TANAH DALAM PERTANIAN BERKELANJUTAN1. Services provided by tillagePrepares the ground for seedlings and transplantsProvides a range of residue incorporation optionsEnables the incorporation of amendmentsImproves soil aeration, and breaks up soil clods to form good seed and root bedsImproves water infiltrationIncreases rate of microbial activity and mineralizationDeep tillage can break through compacted layers2. Disadvantages of tillageAccelerates the rate and extent of long-term declines in soil organic matterMay increase sub-soil compactionHigh energy and labor costsLoss of soil organic matter (SOM) from excessive tillage can lead to crusting of bare soils3. Advantages of reduced and no-tillage systemsResidue cover protects the soil from wind and water erosionAllows for greater moisture retention in rain-fed systemsThese systems build SOM over a period of years, and reach a higher “steady state” level than tilled systems in the same environmentReduced tillage in agricultural soils creates a greater carbon sink4. Limitations of reduced and no-till agriculture systemsResidue cover lowers soil temperature, which delays seed germination and slows seedling growth and may place growers at an economic disadvantageWeed control is very difficult without use of herbicidesRequires specialized equipment to plant through thick layer of residueIncreased leaching of nutrients and herbicides into the groundwater has been shown in someSumber: Diunduh 15/3/2012
20PENGELOLAAN KESUBURAN TANAH Cover Crops dalam Pertanian Berkelanjutan 1. Services provided by cover cropsa) Cover crops increase nutrient availabilityThe role of legume cover crops in biological N fixation and nutrient budgetingNutrients are released into the soil solution as the cover crop residues are broken downCover crops can stimulate microbial activity and increase the breakdown of existing SOMDeep-rooted cover crops are able to recycle nutrients acquired from deeper in the soil profileGrass/cereal cover crops may reduce nutrient losses by capturing mobile nutrients (e.g., nitrate)2. Influences on the nutrient release from cover cropsa) Temperature and moisture conditionsb) Placement of the residueResidue on soil surface: Will decompose more slowly due to dryingIncorporation 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 organismsBelow 6–8 inches: Will decompose more slowly due to lower oxygen levels, fewer decomposersc) Composition/“quality” of the cover crop residueThe 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 NOptimum stage of development to incorporate cover crops = 75%–100% of full bloomThe presence of lignins and tannins in cover crop residue slows decompositionSumber: Diunduh 15/3/2012
21PENGELOLAAN KESUBURAN TANAH Cover Crops dalam Pertanian Berkelanjutan3. The timing of nutrient release, crop demand, and the fate of essential plant nutrientsManaging the timing of nutrient release from cover crops to coincide with crop demandLeaching: Nutrients (N) can become vulnerable to loss if timing is mismatchedNutrient deficiencies: If timing is mismatched, nutrient deficiencies (N) may then result4. Some effects of cover crops on agricultural soilsImprovements to soil physical properties: Carbon and nutrient cycling through the use of cover cropsThe influence of cover crops on disease and pest severityRye, triticale, forage rapeseeds, mustards, and oil seed radish are known to suppress certain plant parasitic nematodes and soil borne diseasesMany legumes can actually increase pest populationsc) Weed-suppressive effects of cover cropsi. Competition for light/smotheringii. Allelopathy5. Importance of gathering regional cover crop informationA 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.Sumber: Diunduh 15/3/2012
22PENGELOLAAN KESUBURAN TANAH KOMPOS DAN PUPUK KANDANG 1. Compostsa) How much compost to apply annuallyb) The nutrient contribution of a manure-based compost: ~1N-1P-1K, i.e., balancedcontribution of N-P-K. As nutrient levels in compost vary, it is recommended thatyou check with supplier or have a compost nutrient assessment done to confirmnutrient levels and proportions.c) Application timing: Nutrient release should ideally coincide with crop demandDepending on compost quality, may be an inefficient source of N in short termRelease of N may last 6 weeks–several months following incorporation, depending on compost quality and environmental conditionsNeed to incorporate into root zone if applying mid season as side dressd) Compost quality indicatorsC:N ratioCO2 levelsAmmonia levelsSmellColorTexture/feelTemperaturee) Ease and economics of usef) Labor and/or equipment requirements for on-farm production of compost.g) National Organic Program standards for on-farm compost productionh) Transportation issues:Local/regional availability and costs;Variability in qualitySumber: Diunduh 15/3/2012
23PENGELOLAAN KESUBURAN TANAH Effect of Manure application on carbon budgets in ecosystemsThe 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, respectivelyRestrictions on the use of manure under National Organic StandardsVariations in the nutrient profiles of animal manures: The nutrient profile of fresh manures range from approximately (horse manure) to (poultry manure).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 tarpsFood safety issue: NOP guidelines designed to prevent contamination by E. coli and other disease-causing organismsPUPUK KANDANGSumber: Diunduh 15/3/2012
24PENGELOLAAN KESUBURAN TANAH Soil Amendments and Supplemental Fertilizers1. Organic amendmentsa) OMRI/NOP-certified materials in certified organic farming systemsb) Nutrient budgeting2. Supplemental fertilizers: When used3. Soil fertility management and nutrient budgets: Balancing nutrient inputs with nutrient outputs each yearInputs > outputs = accumulation. Potential risk of excess nutrients creating nonpoint source pollution through leaching and run off, and enhancing disease and pest incidence.Inputs < outputs = soil depletion. Potential risk of plant nutrient deficiencies and stress, reduced yield, and increased susceptibility to pest and pathogens.Goal: Balance inputs and outputs once you have achieved desired/optimal nutrient levels in the soil. Example of inputs factored into budget for nitrogenInputs = imported fertilizers and amendments + atmospheric deposition + N fixation through cover cropsOutputs = N exported in crop harvest + N lost through leaching, erosion, and denitrificationCalculating nutrient budgets: See Unit 1.11, Reading and Interpreting Soil Test Reports4. 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
25PENGELOLAAN KESUBURAN TANAH PERGILIRAN TANAMAN1. Crop rotation2. Rotation considerationsa) 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 rotationb) 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 rotationsPola pergiliran tanaman sayuran dalam periode lima tahunSumber: Diunduh 15/3/2012
26DINAMIKA HARA TANAHMempertahankan jumlah optimum unsur hara hanya dapat terlaksana dengan menciptakan keseimbangan yang baik antara penambahan dan kehilangannyaBenefits of Organic Matter Reduces compaction and bulk densityProvides a food source for microorganismsIncreases activities of earthworms and other soil crittersBenefits of Organic Matter Increases soil CECStabilizes nutrientsBuilds soil friability and tilthReduces soil splashCarbon 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.Carbon sequestration is the capture of carbon dioxide (CO2) and may refer specifically to:"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.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.Natural biogeochemical cycling of carbon between the atmosphere and reservoirs, such as by chemical weathering of rocks.(http://en.wikipedia.org/wiki/Carbon_sequestration)
27PENTINGNYA PUPUK DAN PEMUPUKAN 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)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
28KETERSEDIAAN UNSUR HARA DAN pH Nutrient availability and soil pHSome 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 AvailabilitySumber: Diunduh 15/3/2012
29Cation Exchange Capacity – Everything You Want to Know and Much More James J. CamberatoClemson University, Crop and Soil Environmental ScienceRINGKASANCation 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
30Organic matter, nutrient contents and cation exchange capacity in fine fractions from semiaridcalcareous soilsF. Caravaca ), A. Lax, J. Albaladejo. Geoderma –176ABSTRACTSoil 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 CrN ratio became smaller as particle size decreased. The higher CrN 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
31POKOK-POKOK PENGELOLAAN KESUBURAN TANAH. Suplai nitrogen dari:Sisa Tanaman Tanaman biasaPupuk kandang Tanaman legumeHujan & irigasi Pupuk hijauPupuk nitrogen Kompos2. Penambahan bahan organik melalui:Sisa tanaman legume dan non legumePupuk kandangPupuk hijau3. Penambahan kapur bila diperlukanBatu kapur kalsit atau dolomit yg biasa dilakukan4. Penambahan fosfat:Pupuk superfosfat, atauPupuk lainnya5. Penambahan kalium tersedia:Pupuk kandangSisa tanamanPupuk Kalium6. Kekurangan belerang diatasi dg:Belerang, gipsum, superfosfat, Amonium sulfat, Senyawa belerangdalam air hujan7. Penambahan unsur mikro: Sebagai garam terpisah atau campuran
32THE 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 phosphorusThe 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 phosphorusBetween 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.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.Sumber: Diunduh 15/3/2012
33Examples of phosphate adsorption mechanisms THE FATE OF PHOSPHATE FERTILISERS IN SOILI.S. Cornforth (Department of Soil Science, Lincoln University)Examples of phosphate adsorption mechanismsSumber: Diunduh 15/3/2012
34THE FATE OF PHOSPHATE FERTILISERS IN SOIL I.S. Cornforth (Department of Soil Science, Lincoln University)The absorption of adsorbed P into soil minerals (a) and the subsequent occlusion of adsorbed P (b)Sumber: Diunduh 15/3/2012
35THE 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 ScienceVOL. 6, NO. 1, JANUARY 2011ABSTRACTThe 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 (PBCK) 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 requirementSumber: Diunduh 15/3/2012
36H. F. Mayland and S. R. Wilkinson. SOIL FACTORS AFFECTING MAGNESIUM AVAILABILITY IN PLANT-ANIMAL SYSTEMS: A REVIEW IH. F. Mayland and S. R. Wilkinson.J. Anita Sei :ABSYRAOTSoils 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
37Fertilizer and Management Practices Effects of Potassium Fertilization on Soil Potassium Distribution and Balance in Pistachio OrchardsDavid Qiupeng Zeng, Patrick H. Brown, and Brent A. HoltzBetter 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.Fertilizer and Management PracticesIncreased 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)Sumber: Diunduh 15/3/2012
38Effects of Potassium Fertilization on Soil Potassium Distribution and Balance in Pistachio Orchards David Qiupeng Zeng, Patrick H. Brown, and Brent A. HoltzBetter Crops/Vol. 83 (1999, No. 4)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.Sumber: Diunduh 15/3/2012
39MENGATASI KEKURANGAN NITROGEN Penambahan & Kehilangan N-tersedia 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.pdf)Penambahan & Kehilangan N-tersediaPengikatan NitrogenPupuk BuatanSimbiotikNon-SimbiotikSisa tanamanPupuk KandangN-tersedia dlm tanahAtmosferBahan OrganikPanen TanamanHilang ErosiHilang Pencucian
40Soil Biology and Biochemistry. Volume 18, Issue 4, 1986, Pages 417–425 The fate of nitrogen from legume and fertilizer sources in soils successively cropped with wheat under field conditionsJ.N. Ladd, M. AmatoSoil Biology and Biochemistry. Volume 18, Issue 4, 1986, Pages 417–425AbstractUsing 15N-labelled legume material (Medicago littoralis) and fertilizers (urea, (NH4)2SO4, KNO3), 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 15N, uptake by crops, distribution as inorganic 15N 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 15N, uptake by both crops was directly related to input; and uptake by the second crop was directly related to the amounts of 15N 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 15N 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 15N, the amounts of inorganic 15N present in soil profiles at sowing in successive years were directly related to 15N inputs. A small but statistically-significant departure from linearity was observed for inorganic 15N at sowing of crop 2 when related to total recoveries of 15N in soils at that time; the higher the amount of 15N recovered, the greater the proportion present as inorganic 15N 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 15N 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 15N atom% enrichments of the inorganic N at sowing in the cropped soils were relatively uniform throughout the profile.Sumber: ….. Diunduh 15/3/2012.
41Soil & Tillage Research 33 (1995) 197-213 Traffic and residue management systems: effects on fate of fertilizer N in cornH.A. Torbert , D.W. Reeves.ABSTRACTSoil 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 15Ndepleted 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.
42N in soil organic matter – How much is released? SOIL ORGANIC MATTER AS A FUNCTION OF NITROGEN FERTILIZATION IN CROP SUCCESSIONSRenato 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. 2005ABSTRACTThe 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 .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: ….. Diunduh 21/3/2012 )Sumber: Diunduh 15/3/2012
43MEMPERTAHANKAN BAHAN ORGANIK TANAH Carbon Inputs to Soil Crop residuesCover cropsCompost , and ManuresCarbon 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 productsOutput mediated by activity of decomposersIt is common that from 40 to 60% of the C taken up by microorganisms is immediately released as CO2.Managing soil carbonNatural 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)
44Soil Quality Technical Note No. 5 Managing Soil Organic Matter The Key to Air and Water QualityUSDA Technical Note No. 5 October 2003Apply practices that enhance soil organic matter• Diverse, high biomass crop rotations• Cover crops• Reduced tillage• Rotational grazingOrganic matter dynamics change• Increased surface residue forms a physical barrier to windand water erosion.• Higher residue rotations and cover crops contribute moreorganic matter and nutrients to the soil.• Less soil disturbance means lower organic matter losses.Soil properties change• Surface structure becomes more stable and less prone tocrusting and erosion.• Water infiltration increases and runoff decreases when soilstructure improves.• Soil organic matter holds 10 to 1,000 times more water andnutrients than the same amount of soil minerals.• Beneficial soil organisms become more numerous and activewith diverse crop rotations and higher organic matter levels.Sumber: ….. Diunduh 15/3/2012
45Strategies for Building Soil Organic Matter Oklahoma Cooperative Extension Fact Sheetsare also available on our website at:Building Soil Organic Matter for a Sustainable Organic Crop ProductionStrategies for Building Soil Organic MatterThe 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 systemIt 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
46APLIKASI BAHAN ORGANIK KE TANAH Oklahoma Cooperative Extension Fact Sheetsare also available on our website at:Building Soil Organic Matter for a Sustainable Organic Crop ProductionAPLIKASI BAHAN ORGANIK KE TANAHThere 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.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)Sumber: … Diunduh 15/3/2012
47TANAMAN PENUTUP TANAH DAN PUPUK HIJAU Oklahoma Cooperative Extension Fact Sheetsare also available on our website at:Building Soil Organic Matter for a Sustainable Organic Crop ProductionTANAMAN PENUTUP TANAH DAN PUPUK HIJAUA 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.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)Sumber: … Diunduh 15/3/2012
48Maintaining and Monitoring Soil Organic Matter Oklahoma Cooperative Extension Fact Sheetsare also available on our website at:Building Soil Organic Matter for a Sustainable Organic Crop ProductionMaintaining and Monitoring Soil Organic MatterOnce 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.Sumber: … Diunduh 15/3/2012
49Microbial biomass – a significant source for soil organic matter Matthias Kaestner and Anja MiltnerGeophysical Research AbstractsVol. 13, EGU , 2011ABSTRACTThe 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.AbstractCharacterization 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) 13C 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
51Sisa tanaman & Pupuk Kandang Ca dan Mg tersedia dalam tanah 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)PENTINGNYA Ca & MgPenambahan dan kehilanganSisa tanaman & Pupuk KandangPupuk KomersialMineral TanahCa dan Mg tersedia dalam tanahKAPURPANEN TANAMANHilang pencucianHilang Erosi
52Effects 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, 2010ABSTRACTWine 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: ….. Diunduh 15/3/2012
53Dolomite Lime’s Reaction Applied on the Surface of a Sandy Soil of the Northwest Paraná, BrazilAnderson 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 2002ABSTRACTLow 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
54L. B. Fenn and E. Wu. Biology and Fertility of Soils. Effect of ammonium fertilizer on NH3 loss and Ca, Mg, ammonium and nitrate content in a calcareous soil solutionL. B. Fenn and E. Wu. Biology and Fertility of Soils.Volume 5, Number 2,AbstractThis study examined the effects of NH inf4 + fertilizers [(NH4)2SO4, (NH4)2HPO4, CO(NH2)2, NH4OH, and NH4NO3] on NH3 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 NH4 fertilizers applied at a depth of 5 cm in the soil produced differing NH3 loss characteristics. Applying (NH4)2SO4 (AS) resulted in high volatile NH3 losses as compared with NH4OH (AH) and (NH4)2CO3 (AC). The AS treatment formed an equal molar amount of CaSO4, which increased the mobility of ammonium, while AH and AC treatments caused Ca precipitation and decreased ammonium mobility.Leaching the AS system before NH3 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 NH4 fertilizers resulted in variable leachate contents of Ca + Mg. Ammonium sulfate reacted with CaCO3 either to solubilize some Ca + Mg or simply to replace exchangeable Ca + Mg with NH4, while AH, AC, and (NH4)2HPO4 (DAP) precipitated essentially an equivalent molar amount of soluble and adsorbed Ca + Mg.Use of NH4NO3, 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
55MEMPERTAHANKAN KETERSEDIAAN FOSFAT. Kehilangan & Penambahan P-tersedia Sisa tanamanPukuk kandangPukuk komersialMineral P-tanahBahan Organik TanahP-tersedia dalam tanahTerangkut tanamanHilang PencucianHilang ErosiFiksasi
56Plants require adequate P from the very early stages of growth 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–ABSTRACTPlants require adequate P from the very early stages of growthfor 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
57Soil and fertilizer phosphorus: Effects on plant P supply and mycorrhizal development by C Grant, S Bittman, M Montreal, C Plenchette, C MorelCanadian Journal of Plant Science (2005)Volume: 85, Issue: 1, Pages: 3-14ABSTRACTPlants 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
58Journal of Cambridge Studies. Vol.6 No.2-3 2011 The Effect of Farmland Management on Soil Phosphorus Runoff in Taihu Basin*Lixia YANGJournal of Cambridge Studies. Vol.6 NoABSTRACTPhosphorus 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
59Sisa tanaman & Pupuk Kandang KETERSEDIAAN KALIUMTanah mineral umumnya mengandung cukup banyak kalium, kisaran 40 ton setiap hektar lapisan olah tanah. Namun demikian hanya sebagian kecil yangtersedia bagi tanamanKehilangan & Penambahan Kalium:Sisa tanaman & Pupuk KandangPupuk komersialMineral-Klambat tersediaK-tersedia tanahTerangkut tanamanKehilangan pencucianKehilanganerosiKehilanganFiksasi
60Factors Affecting K Availability Potassium Releasing Capacity in Some Soils of Anantnag District of Kashmir. Subhash Chand and Tahir AliUniversal Journal of Environmental Research and Technology Volume 1, Issue 3:AbstractThe 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.Factors Affecting K AvailabilitySoil 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.Soil test K:Higher soil test K increases the available K, by increasing the amount and balance of K relative to other cations.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.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.Soil pH: As the soil pH is reduced (increasing soil acidity) the availability of K is often reduced.Soil Temperature: Cold soils often reduce the availability of K.Soil compaction: Compacted soils often reduce the availability of K.Soil Drainage/Aeration: As soil drainage is improved, K uptake typically improves.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)Sumber: Diunduh 15/3/2012
61Canadian Journal of Soil Science, 1958, 38(1): 36-43 RATE OF RELEASE OF NON-EXCHANGEABLE POTASSIUM BY ONTARIO SOILS IN RELATION TO NATURAL SOIL CHARACTERISTICS AND MANAGEMENT PRACTICESH. B. McEwen, B. C. MatthewsCanadian Journal of Soil Science, 1958, 38(1): 36-43AbstractThe 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.Relationship among unavailable, slowly available, and readily available potassium in the soil-plant system.(sumber: diunduh 21/3/2012)Sumber: Diunduh 15/3/2012
62Nepal Agriculture Research Journal Vol.7 2006 pp.42-48 Effect of Potassium on Potato Tuber Production in Acid Soils of Malepatan, PokharaB.H. Adhikari, K.B. KarkiNepal Agriculture Research Journal Vol pp.42-48AbstractSoils 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 (K2O) 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 (P2O5) 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 (K2O) 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
63JWSS - Isfahan University of Technology, 2001; 5 (3) :79-93 . Potassium Fixation and Charge Characteristics of Clay in some Soils of Central and Northern Iran A. Hosseinpur and M. KalbasiJWSS - Isfahan University of Technology, 2001; 5 (3) :79-93AbstractPotassium 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 KThe 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. 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.Sumber: …http://jstnar.iut.ac.ir/browse.php?a_code=A &slc_lang=en&sid=1.. Diunduh 17/3/2012
64. Factors of soil potassium regime in intensive fertilization. Hudcová, O.Journal Rostlinná Výroba 1990 Vol. 36 No. 2 ppAbstractThe 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
65Potassium 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 AnalysisVolume 41, Issue 16, pagesAbstractPotassium (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 K2O were accommodated in pots that received 90 kg ha−1 of K2O. 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
66Jurnal Ilmu Tanah & Lingkungan, Vol 9, No 1 (2007). Phosphorus and Potassium Status in Paddy Soils (Sawah) of Central Lampung RegencyJunita BarusAbstractThe 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 P2O5/100 g. High K 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
67ISAAC BARSHAD and FAWZY M. KISHK Clays and Clay Minerals, 1970, Vol. 18, ppFACTORS AFFECTING POTASSIUM FIXATION AND CATION EXCHANGE CAPACITIES OF SOIL VERMICULITE CLAYSISAAC BARSHAD and FAWZY M. KISHKAbstract-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 In 1 teaspoon of soil there are… 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 & amoebaOne to several hundred ciliates ……. Protozoa 6-9 ft fungal strands put end to end ………. Fungi 100 million to 1 billion …………. BacteriaA 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.Sumber: … diunduh 18/3/2012
69Classical C Pools Nonhumic substances—carbohydrates, lipids, proteins Humic substances—humic acid, fulvic acid, huminBOT berpengaruh terhadap:-Plant nutrition-Soil and Plant health-Soil physical, chemical and biologicalpropertiesGraph of Relative Available N with Length of Time for DecompositionGambar diambil dari: Understanding Soil Microbes and Nutrient Recycling (James J. Hoorman and Rafiq Islam The Ohio State University)Sumber: …. Diunduh 18/3/2012
70BOT ----- 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 residuesSumber: Diunduh 18/3/2012
71BOT --- 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
72Proteins & Nucleic acids 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.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.ConstituentsMicroorganismsBacteriaFungiActinomycetesCelluloseAchromobacter, Bacillus, Cellulomonas, Cellvibrio, Clostridium, Cytophaga, Vibrio Pseudomonas, Sporocytophaga etc.Aspergillus, Chaetomium, Fusarium, Pencillium Rhizoctonia, Rhizopus, Trichoderma, Verticilltttm.Micromonospora, Nocardia Streptomyces, ThermonosporaHemicelluloseBacillus, Achromobacter, Cytophaga Pseudomonas, Erwinia, Vibrio, LactobacillusAspergillus, Fusarium, Chaetomium, Penicillium, Trichoderma, HumicolaStreptomyces, ActinomycetesLigninFlavobacterium, Pseudomonas, Micrococcus, Arthorbacter, XanthomonasHumicola, Fusarium Fames, Pencillium, Aspergillus, GanodermaStreptomyces, NocardiaStarchAchromobacter, Bacillus, ClostridiumFusarium, Fomes, Aspergillus, RhizopusMicromonospora, Nocardia, Streptomyces,PectinBacillus, Clostridium, PseudomonasFtisarium, VerticillumChitinBacillus, Achromobacter, Cytophaga, PseudomonasMucor, Fusarium, Aspergillus, TrichodermaStreptomyces, Nocardia, MicromanosporaProteins & Nucleic acidsBacillus, Pseudomonas, Clostriddum, Serratia, MicrococcusPenicillium, Rhodotorula,StreptomycesSumber:
73Fungi tend to be selected for by plant residues with high C/N ratios. 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 (<20) will decompose in 4 to 8 weeks and result in net mineralization or release of N. Sudan grass or cereal rye with a higher 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
74Bacteria 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
75KANDUNGAN BOTHow 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: Diunduh 21/3/2012)
76PENTINGNYA BOTOrganic 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 conditionsSoil organic matter is extremely important in all soil processesCultivation can have a significant effect on the organic matter content of the soilIn essentially warm and dry areas like Southern Europe, depletion of organic matter can be rapid because the processes of decomposition are accelerated at high temperaturesGenerally, plant roots are not sufficiently numerous to replace the organic matter that is lostImproving organic matter in your soil There are many management practices you can do to improve SOM on your property. Practices that may increase soil organic matter include:Reducing or eliminating tillageMaintaining vegetative coverProtect soil from fireStubble retentionAdding manures or other organic matter sourcesRestrict grazingControl insects and rodents(http://vro.dpi.vic.gov.au/dpi/vro/vrosite.nsf/pages/soilhealth_practical-note-soil-organic-matter ….. Diunduh 19/3/2012)
77MANFAAT BOT Storehouse for nutrients Source of fertility Contributes to soil aeration thereby reducing soil compactionImportant ‘building block’ for the soil structureAids formation of stable aggregatesImproves infiltration/permabilityIncrease in storage capacity for water.Buffer against rapid changes in soil reaction (pH)Acts as an energy source for soil micro-organismsUnderstanding Soil Microbes and Nutrient Recycling (James J. Hoorman and Rafiq Islam The Ohio State University)Sumber: …. Diunduh 18/3/2012
78Degradation: HILANGNYA BOT During field operations, fresh topsoil becomes exposed and dries rapidly on the surfaceOrganic compounds are released to the atmosphere result from breakdown of soil aggregates bound together by humic materialsUnless the organic matter is quickly replenished, the system is in a state of degradation leading eventually to un-sustainabilityThe 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 depletionLong-term effect of tillage, crop rotations and fertilizer application on soil organic matter.Sumber: Diunduh 18/3/2012
79FAKTOR YG PENGARUHI BOT Natural factors:ClimateSoil parent material: acid or alkaline (or even saline)Land cover and or vegetation typeTopography – slope and aspectHuman-induced factors:Land use and farming systemsLand management (cultivation)Land degradationThe 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)
80FAKTOR IKLIM PENGARUHI BOT: Temperature:OM decomposition rapid in warm climatesOM Decomposition is slower for cool regionsResult:Within zones of uniform moisture and comparable vegetation --Av total OM increases 2x to 3x for each 10 deg C fall in mean temperatureMoisture:Under comparable conditionsAv total OM increases as the effective moisture increasesAdequate 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.AIR TANAHSUMBER: …. DIUNDUH 18/3/2012
81Sumber: 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 ratioSUMBER: …. DIUNDUH 18/3/2012
82Sumber: www.cartage.org.lb/en/themes/sci...ones.htm Structure of soil, indicating presence of bacteria, inorganic, and organic matterSumber: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 TanahSUMBER: …. DIUNDUH 18/3/2012
83Sumber: SOIL FERTILITY MANAGEMENT PUPUK KANDANGManure 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.The goals of applying manure are to:increase the level of organic matter;increase the available nutrients;improve the structure (aggregate formation) and water retention capacity of the soil.Sumber: SOIL FERTILITY MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
84KEUNTUNGAN MENYIMPAN DAN MEMATANGKAN PUPUK KANDANG Fresh stable manure is not very suitable for immediate use. The C:Nratio of fresh manure is high, which can cause nitrogen immobilisation.If the organic matter is very rough i.e. it contains a lot of fibreand 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 MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
85KOMPOSCompost 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
86KEUNTUNGAN KOMPOSTING Sumber: SOIL FERTILITY MANAGEMENT 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: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.Rats and mice can nest in thick layers of leaves or mulch. This is not a problem with compost.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).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.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 MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
87KETERBATASAN KOMPOSTING Sumber: SOIL FERTILITY MANAGEMENT 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.The compost heap can also be made in a period when there is not very much other work to be done.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.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.Kelemahan Pembuatan Kompos: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.Time Involved : Composting requires a time commitment to properly manage the windrows to produce quality compost.Cost of Equipment : Specialized windrow turners may be required, but they can come at with a high price tag.Land Required : The composting site and storage for finished product can use a considerable area of land.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)Sumber: SOIL FERTILITY MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
88Sumber: SOIL FERTILITY MANAGEMENT KESEIMBANGAN HARATo 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:removal of the harvest (all of the nutrients);volatilisation (especially N; this happens especially during burns due to the high temperatures);run-off (especially N);fixation (especially P);leaching;erosion (all nutrients).Hara ditambahkan ke tanah melaluii proses:decomposition of organic matter (all nutrients);nitrogen fixation (only N);weathering (mostly K and Mg);chemical fertiliser (mostly N, P, and K);rain and solid matter deposits.Sumber: SOIL FERTILITY MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
89Sumber: SOIL FERTILITY MANAGEMENT PUPUK HIJAUGreen manuring consists of ploughing in green, not woodyplants 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:make nutrients available for the main crop;improve the soil structure;increase or retain the level of organic matter in the soil;increase the ability of the soil to retain moisture;protect the soil against rain and wind erosion, dehydration and extreme temperature fluctuations at a time when no other crops are present;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 MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
90KEUNTUNGAN PUPUK HIJAU Green ManuresAny 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)Keuntungan Pupuk HijauDuring their growth period, green manures provide the same benefits as mulch. They are therefore sometimes called .living mulch..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.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 MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
91KETERBATASAN PUPUK HIJAU Sumber: SOIL FERTILITY MANAGEMENT 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.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.Tanaman jagung dengan pupuk hijauSumber: SOIL FERTILITY MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
92Azolla: green manure profile Sumber: SOIL FERTILITY MANAGEMENT APLIKASI PUPUK HIJAUIt 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.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.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.Azolla: green manure profileAzolla 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: 21/3/2012)Sumber: SOIL FERTILITY MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
93Sumber: SOIL FERTILITY MANAGEMENT APLIKASI PUPUK HIJAUThe 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 MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
94Sumber: SOIL FERTILITY MANAGEMENT APLIKASI PUPUK HIJAUIf 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 MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
95Sumber: SOIL FERTILITY MANAGEMENT INTERCROPPINGIntercropping 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.Important goals of intercropping are:A direct production increase compared to monoculture (if enough water is available), due to:better ground cover;optimum use of sunlight;more efficient root growth;extra nitrogen (when using nitrogen-fixers);Spreading the risks of crop failure over more crops, due to:multiple crops; if one crop fails the other might still yield something;limited effect of diseases and pests because one pest or disease is mostly specialised on one crop and will leave a different crop unharmed.Schematic representation of vertical root distribution of cacao intercropped with coconut (Nelliat et at. 1974).(http://www.fao.org/docrep/005/af298e/af298E01.htm)Sumber: SOIL FERTILITY MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
96MANFAAT INTERCROPPING Sumber: SOIL FERTILITY MANAGEMENT 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.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.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.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.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.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 peaksSumber: SOIL FERTILITY MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
97KERUGIAN INTERCROPPING One disadvantage is that the denseness of the crops makes it physically more difficult to combat diseases, pests and weeds.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.Yield decreases as the crops differ in their competitive abilities.Management of I/c having different cultural practices seems to be difficult task.Improved implements cannot be used efficiently.Higher amount of fertilizer or irrigation water cannot be utilized properly as the component crops vary in their response of these resources.Harvesting is difficult.(http://www.agriinfo.in/?page=topic&superid=1&topicid=662)Disadvantages of intercropping:Sumber: SOIL FERTILITY MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
98Sumber: SOIL FERTILITY MANAGEMENT METODE INTERCROPPINGA 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.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.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.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)Sumber: SOIL FERTILITY MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
99The role of organic mulches Sumber: SOIL FERTILITY MANAGEMENT MULSA DAN APLIKASINYAMulching 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:Improve infiltration;Protect the soil from water and wind erosion and from dehydration;Prevent high ground temperatures;Increase the moisture level in the soil; and, when mulching with organic material, to:Increase or retain the level of organic matter in the soil;Better utilise the nutrients from chemical fertiliser;Stimulate soil organisms.The role of organic mulchesMulches have many beneficial effects upon the soil, plants and area surrounding the plants.They conserve soil moisture by reducing evaporation of water from the soil.They prevent crusting of the soil surface, thus improving absorption and percolation of water to the soil areas where the roots are growing.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.They prevent fruits and plants from becoming mud splashed and reduce losses from soil-borne diseases.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: Diunduh 21/3/2012)Sumber: SOIL FERTILITY MANAGEMENTLaura van Schöll, Rienke Nieuwenhuis. Agromisa Foundation, Wageningen, 2004.
100Sumber: SOIL FERTILITY MANAGEMENT KEUNTUNGAN MANFAAT MULSACovering 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.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.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.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.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, ppSumber: SOIL FERTILITY MANAGEMENTLaura van Schöll, Rienke Nieuwenhuis. Agromisa Foundation, Wageningen, 2004.
101KETERBATASAN DAN KERUGIAN MULSA Sumber: SOIL FERTILITY MANAGEMENT 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.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.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), pBriscoe, C.B Field trials manual for multipurpose tree species. Multipurpose tree species network research series; manual no. 3. Winrock International. Bangkok, Thailand.Sumber: Diuinduh 21/3/2012Sumber: SOIL FERTILITY MANAGEMENTLaura van Schöll, Rienke Nieuwenhuis. Agromisa Foundation, Wageningen, 2004.
102TEKNOLOGI APLIKASI MULSA Sumber: SOIL FERTILITY MANAGEMENT Method and recommendationsThe mulch has to be applied before the rainy season begins, becausethe soil is then most vulnerable. The seeds can be sown through themulch layer by making small openings in the mulch through which theseeds are planted. After planting each seed the opening must beclosed, otherwise birds will become aware of the presence of the seed.The mulch layer may not be too thick. A sufficient amount would almostcompletely cover the soil from sight. If the layer is too thick, itwill be difficult for the sprouted plants to reach the surface. The seedscan also be sown in rows that have been cleared by ploughing or removing the mulch.Applying MulchesApply 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)Sumber: SOIL FERTILITY MANAGEMENTLaura van Schöll, Rienke NieuwenhuisAgromisa Foundation, Wageningen, 2004.
103The plant nutrient balance system Food, Agriculture, and the Environment Discussion Paper 32Integrated Nutrient Management, Soil Fertility, and Sustainable Agriculture: Current Issues and Future Challengesby Peter Gruhn, Francesco Goletti, and Montague YudelmanInternational Food Policy Research Institute K Street, N.W.Washington, D.C U.S.A. September 2000The plant nutrient balance systemSmaling, 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
104Soils: Fertility Management MSU EXTENSION SERVICES October 14, 2010.Use soil testing to assess fertility status.Use common-sense, attainable yield goals.Determine nutrient and moisture content of manure.Base nutrient applications (either manures or purchased fertilizer) on crop needs as determined by the soil test.Rotate fields receiving manure to avoid nutrient buildup and maximize nutrient utilization.Use only sufficient fertilizer required for attainable crop yield goals.Incorporate fertilizer and manure when possible.Calibrate all application equipment.Avoid applying fertilizer, or manure, on wet soils to minimize compaction, runoff and leaching/denitrification.Avoid applying fertilizers and manure near streams, ponds, or other water bodies.Use grass filter strips along ditches and waterways to reduce soil erosion, runoff and nutrient losses.Time applications to when nutrients are needed by the crop as possible.Utilize fall cover crops to minimize soil erosion and runoff and to maximize nutrient utilization from manure applications.BMP Kesuburan TanahSumber: ….. Diunduh 17/3/2012
105Nutrient Management Guidelines for Agronomic Crops Grown in MississippiLarry Oldham, Ph.D.Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State UniversityNutrient 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 17/3/2012
106Nutrient Management Guidelines for Agronomic Crops Grown in MississippiLarry Oldham, Ph.D.Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State UniversitySteps in Nutrient Management Planning1) Obtain accurate soil information for each field or management unit.a. Create farm maps that include soil series, surface water bodies, and other resource concernspresent in the landscape.b. Sample the soil in each field or management unit and process through a reputable soil-testinglaboratory. Some government programs in the state require testing through the MississippiState University Extension Service Soil Testing Laboratory.2) Develop fair, realistic estimated crop yield goals for each field based on recent productionhistory, agronomic practices, and soil characteristics. The key is to be realistic. The past three tofive years of production data may be used to develop an average baseline.3) Using the soil test analyses, determine the plant nutrients required to reach the yield goal. In somecases, you may need to take into consideration nutrient uptake and removal data for commoncrops. This information is available from various sources, including Chapter 3 of this manual. Itis important to distinguish between crop uptake and nutrient removal in harvested biomass.4) Determine plant-available nutrients from any livestock byproduct amendments that will be usedto 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. See alsoChapter 7. More information on testing broiler litter is available at Soil and Broiler Litter TestingBasics (MSU Extension Service Information Sheet 1614)n n n45) Estimate nutrient contributions from manures that were applied in previous seasons. Usually50 to 60 percent of nitrogen in animal manures is available to growing plants the first year followingapplication. Residual nutrients are usually available on a declining scale for about threegrowing seasons. In some circumstances, the MSU Extension Service credits carryover fromearlier inorganic fertilizer applications. (See individual crop recommendations for specifics.)6) Environmental assessment tools, such as the Mississippi Phosphorus Index (PI), can calculate thepotential risk of offsite phosphorus movement on a field-by-field basis. The PI incorporates sitespecificsoil conditions and applied BMPs in the evaluation. Soil test phosphorus levels, soilpermeability, field slopes, litter application rates, distance to surface water, and other factorsare used to determine the probability of nutrient movement. If the PI shows low risk, NMP maybe based on crop nitrogen needs for optimal production. If the PI is medium risk, additional BMPsmay be necessary. If the PI shows high potential risk for P movement in the landscape, NM shouldbe based on crop P requirements as determined by the soil test recommendations.7) Apply animal manures and commercial fertilizers based on soil-test recommendations and therisk assessment. Over-application does not improve yields and increases the risk ofenvironmental problems.8) Keep records of nutrient sources, application dates, rates, methods, and general climaticconditions. Good records simplify planning.Sumber: ….. Diunduh 17/3/2012
107Nutrient Management Guidelines for Agronomic Crops Grown in MississippiLarry Oldham, Ph.D.Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State UniversityBest Management Practices for Nutrients in Agronomic Crop ProductionThe 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, and3) 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:• Are the fertilizers necessary?• How much fertilizer is economical?• What fertilizers are available?• When is the best time to apply the fertilizer?• How can I maximize effectiveness?Sumber: ….. Diunduh 17/3/2012
108Nutrient Management Guidelines for Agronomic Crops Grown in MississippiLarry Oldham, Ph.D.Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State UniversityMatch Nutrients Supplied by Fertilizers to Crop Nutrient Requirements• Soil testingFields should be tested for pH, P, K, and other nutrients at least every three years and preferably moreoften. Information for first-time soil testers is available in Chapter 4, at local Extension offices, and at• Analyze animal byproductsPoultry production is the only consistent source of animal byproducts available in bulk in Mississippi toprovide 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. The Mississippi State ChemicalLaboratory or commercial laboratories can complete this analysis. Information on sampling litter for nutrientanalysis is available at• Nutrient budgetingSoil testing, manure analysis, nutrient uptake, and nutrient removal data accounts for all nutrient sourcesand outflows. This information makes it possible to calculate application rates, particularly if animal manuresare to be used, and allows “what-if” analysis of different rate application scenarios.n n n28• Develop and use realistic yield goalsThe Mississippi State University Extension Service bases fertilizer recommendations or N on yieldgoals for agronomic crops. Including yield goals makes the recommendations site-specific; soiltexture differences are included in the rate calculations for cotton. Some cooler, drier states nolonger use yield goals when recommending N, but yield goals are important in Mississippi, wherethe humid climate makes predicting levels of residual N more difficult.It is important to use realistic yield goals when you calculate application rates. Average thecrop yields from the past 3 to 5 years. Add 10 percent for a realistic projection of the productionpotential of your soils, management, and climate. If past yields are not available, contact the localoffices mentioned above for information on the specific capabilities of different soil series.• Plant nutrient analysisChemical analysis of plant nutrient concentrations in tissue, along with soil testing, may evaluate the soil fertilityprogram and nutrient availability. It is most valuable when “good” and “bad” sections of a growingfield can be contrasted. Information on plant diagnostic sampling is available atSumber: ….. Diunduh 17/3/2012
109Nutrient Management Guidelines for Agronomic Crops Grown in MississippiLarry Oldham, Ph.D.Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State UniversityManage fertilizer applications wisely• Soil test based recommendationsEach 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 neededby the plants. A score of very high means plants probably will not respond to additional fertilizer; a scoreof 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 most Mississippi crops(Appendices A and B). Medium means there may or may not be a response; for soil in this category, MSUrecommends 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 testsmedium, low, or very low, the MSU Extension Service will make P and K application rate recommendationsbased on soil fertility maintenance for the next scheduled crop. If the soil tests very low, the MSU ES recommendationsalso include a small amount of fertilizer for buildup. Other soil testing laboratories in Mississippimay provide different recommendations from the public laboratory.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 situationUsually, when different fertilizer sources of the same nutrient appear to work differently, it’s because theinherent differences between the fertilizer materials are not taken into consideration. Plants cannot tellthe difference between sources of a particular nutrient. Nutrient ions, such as nitrate or phosphate, areall the same when they are in the soil solution, no matter what their source. N fertilizer efficiency especiallydepends on the product and how it is managed.Mississippi State University Extension Service recommendations for N fertilizer management are notbased on soil tests. The state is warm and humid, so N soil testing techniques have had29limited 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 ammoniagas, which drifts away from the field. This loss increases when these fertilizers are applied at temperatureshigher than 65 °F, on fields with a large amount of organic matter or surface residues, or in high humidity.Much more information on commercial fertilizer properties and management issues is available inthe Mississippi State University Extension Service Publication Inorganic Fertilizers for Crop Production.• Proper placement of fertilizersCorrect fertilizer placement is crucial to efficiency. Avoid broadcast sprays of UAN solutions on hot, drydays unless the material will be cultivated in, irrigated in, or rain is imminent. Incorporating animal manurefertilizers helps prevent their movement in the landscape. Avoid applying fertilizer materials toonear to surface water bodies.• Proper application timingThe timing of fertilizer applications is important because the nutrients’ availability to the plants decreaseover time. Nitrogen is especially efficient when it is applied close to the time of crop up take. Applying Ntoo early increases the probability it will leave the field, and supplemental N fertilizer may be necessarylater in the growing season. Fall application of N is not practical in Mississippi for crops seeded in thespring, whether the fertilizer is organic or inorganic. Recent Mississippi research has confirmed that theN 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 notmobile in the soil. However, P fixation in soils is common, so P is not very efficient no matter when it isapplied.In contrast to P fertilizers, K fertilizer effectiveness is not affected by soil fixation except in some highclay content soils. Inorganic potash fertilizers for spring crops may be field applied in the fall if the soilCation Exchange Capacity (CEC) is 8 or higher; it may be lost via leaching at lower CEC values.• Equipment maintenance and calibrationEquipment maintenance and calibration are key to efficient nutrient applications. Know the correct applicationwidth for the equipment and the material being applied; avoid overlaps within the field and ontofield borders. Ensure that belts and chains are properly maintained and adjusted. The Mississippi Departmentof Agriculture and Commerce Bureau of Plant Industry can teach you more about calibrating commercialspreaders, including aerial equipment.• Precision technologyPrecision technologies may allow more efficient fertilizer management of nutrient deficient, acidic, ormore responsive soil areas. However, these tools, which can include management software, special equipment,consultants, soil maps, and training, may be very expensive.Sumber: ….. Diunduh 17/3/2012
110Nutrient Management Guidelines for Agronomic Crops Grown in MississippiLarry Oldham, Ph.D.Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State UniversityMinimize the potential transport of nutrients from fields to water bodiesConservation tillageSome nutrients, such as P ions, are closely bound to soil particles, so soil management that minimizes erosionalso minimizes movement of those nutrients. These management practices include strip-tillage, mulchtillage, no-tillage, or ridge-tillage. More information about conservation tillage is available through local ExtensionService or Natural Resource Conservation Service offices.Proper storage of animal by-productsProper storage of poultry litter is important. Many poultry growers have dry stack sheds to store litter,but farmers acquiring litter may need to storeit temporarily. Recent research by Auburn Universityfound that litter should be covered withplastic or other materials to protect its nutrientcontent. See Chapter 7 for more information.Control water flow on and off fieldsControlling water flow with surface and subsurfacedrainage management reduces nutrient,pathogen, and pesticide runoff intodownstream waters. Proper water control alsoreduces wind erosion and dust and may provideseasonal wildlife habitat. More informationabout conservation tillage and other watercontrol devices, such as weirs, is availablethrough local Extension Service or Natural ResourceConservation Service offices.• Maintain buffersPlanted buffers between nutrient applicationsand nearby water bodies reduce sheet and rillerosion and lower the rate of sediment delivery.Planted buffers may use nutrients that movefrom planted areas and would otherwise entersurface waters. As with other BMP’s, contactlocal agency offices or groups such as DeltaF.A.R.M. for more detailed information onbuffer installation and cost-share programs.• Conservation tillage• Proper storage of animal by-products• Control water flow on and off fieldsSumber: ….. Diunduh 17/3/2012
111Nutrient Management Guidelines for Agronomic Crops Grown in MississippiLarry Oldham, Ph.D.Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State UniversityMississippi State University Extension Service SoilTesting-Based Recommendations for Hay and Pasture CropsSumber: ….. Diunduh 17/3/2012
112Nutrient Management Guidelines for Agronomic Crops Grown in MississippiLarry Oldham, Ph.D.Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State UniversityMississippi State University Extension Service Soil Testing-Based Recommendations for Annual Agronomic CropsSumber: ….. Diunduh 17/3/2012
113Nutrient Management Guidelines for Agronomic Crops Grown in MississippiLarry Oldham, Ph.D.Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State UniversityMississippi State University Extension Service Soil Testing-Based Recommendations for Annual Agronomic CropsSumber: ….. Diunduh 17/3/2012
114Nutrient Management Guidelines for Agronomic Crops Grown in MississippiLarry Oldham, Ph.D.Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State UniversityMississippi State University Extension Service Soil Testing-Based Recommendations for Annual Agronomic CropsSumber: ….. Diunduh 17/3/2012
115Nutrient Management Guidelines for Agronomic Crops Grown in MississippiLarry Oldham, Ph.D.Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State UniversityMississippi State University Extension Service Soil Testing-Based Recommendations for Annual Agronomic CropsSumber: ….. Diunduh 17/3/2012
116Nutrient Management Guidelines for Agronomic Crops Grown in MississippiLarry Oldham, Ph.D.Extension Soils Specialist, Department of Plant and Soil Sciences, Mississippi State UniversityMississippi State University Extension Service Soil Testing-Based Recommendations for Annual Agronomic CropsSumber: ….. Diunduh 17/3/2012
117Base nitrogen application rates on realistic yield goals. Quality Water for Idaho Current Information Series No Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler. Summary of Nitrogen Best Management Practices for the Protection of Groundwater Apply nitrogen at recommended rates for crop production in Idaho. 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
118Quality Water for Idaho Current Information Series No Quality Water for Idaho Current Information Series No 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
119Fertilizer recommendations based on research Quality Water for Idaho Current Information Series No Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. MahlerSpecific types of BMPs for nitrogen fertilizer management that should be employed in many areas of Idaho include:Soil samplingFertilizer recommendations based on researchTiming of fertilizer applicationFertilizer placementNutrient credits for legumes and manuresNitrification inhibitorsManure managementIrrigation systems managementSlow-release nitrogen fertilizersCrop rotation selectionVariable fertilizer managementSumber: ….. Diunduh 17/3/2012
120Quality Water for Idaho Current Information Series No Quality Water for Idaho Current Information Series No 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
121Quality Water for Idaho Current Information Series No Quality Water for Idaho Current Information Series No 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 Idaho 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 Idaho 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
122Quality Water for Idaho Current Information Series No Quality Water for Idaho Current Information Series No Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler. Timing of Fertilizer Application 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
123Quality Water for Idaho Current Information Series No Quality Water for Idaho Current Information Series No Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler. Fertilizer Placement 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
124Quality Water for Idaho Current Information Series No Quality Water for Idaho Current Information Series No Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler. Nutrient Credits for Legumes and Manures Effective use of nitrogen fertilizer requires consideration of nitrogen supplied in manure applications and by legume crops in the rotation. Observations in other areas of the United States 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.Nitrification Inhibitors 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
125Quality Water for Idaho Current Information Series No Quality Water for Idaho Current Information Series No Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler. Manure Management 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. Information on how to calculate manure application rates in the Pacific Northwest can be found in PNW 239, How to Calculate Manure Application Rates in the Pacific Northwest.Irrigation Systems Management 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
126Quality Water for Idaho Current Information Series No Quality Water for Idaho Current Information Series No Nov 1992 Best Management Practices for Nitrogen Management to Protect Groundwater R. L. Mahler, T. A. Tindall, and K. A. Mahler. Slow-Release Nitrogen Fertilizers 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.Crop Rotation Selection 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.Variable Fertilizer Management 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
127Best Management Practices for Phosphorus Fertilization COLORADO STATE UNIVERSITY EXTENSIONBulletin #XCM-175Reagan M. Waskom and Troy BauderBest Management Practices for Phosphorus FertilizationPhosphorus (P) is an essential nutrient for all forms of terrestriallife and is one of the 18 chemical elements known tobe required for plant growth. In Colorado, agricultural soilsgenerally contain from 800 to 2,000 pounds of total P peracre in the tillage layer. However, most of it is in insolublecompounds unavailable to plants. The remainder cycleswithin plants, animals, soil, and the soil solution in biologicallyavailable forms and organic P compounds. A simplifiedP cycle is depicted in Figure 1, showing the principal P inputsand sinks. In production agriculture, fertilizer and manureare the major P additions to this cycle. Without these inputs,intensive commercial agriculture would not be viable onmany soils. However, proper management of soils and P fertilizersis essential to protect water quality from degradation.Water quality problems associated with phosphorusare generally confined to surface water. Phosphorus in mostColorado soils is tightly held to soil particles and does notleach. However, the P held in organic phases from residuessuch as manure can dissolve in water and be lost if improperlymanaged. Adsorbed P on soil particles can cause surfacewater contamination as P containing sediments move off theland in agricultural runoff. When large amounts of nutrientsenter lakes and streams, they accelerate the natural aging process,or eutrophication, by enhancing the growth of algae andother aquatic weeds. As these plants flourish, depleted oxygenand light reduce the survival of more desirable species andthe natural food chain declines. Eventually, impounded waters such as lakes, ponds, and reservoirs become overgrownwith aquatic vegetation and, in a sense, die.Sumber: ….. Diunduh 17/3/2012
128COLORADO STATE UNIVERSITY EXTENSION Bulletin #XCM-175 Reagan M. Waskom and Troy BauderPhosphorus in Agricultural SoilsWhen 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 cropsCrop Yield P removed(per acre) (lb P2O5/A)Alfalfa 4 tons 40Corn (grain) 190 bu 70Corn (silage) 30 tons 120Barley 100 bu 40Bromegrass/fescue 4 tons 40Potatoes 400 cwt 55Sugarbeets 25 tons 35Sunflowers 2,000 lb 80Wheat 100 bu 85Source: Adapted from BMP for Manure Utilization 568ASumber: Diunduh 17/3/2012
129Managing Fertilizer to Reduce Phosphorus Losses and Maximize Returns COLORADO STATE UNIVERSITY EXTENSIONBulletin #XCM-175Reagan M. Waskom and Troy BauderManaging Fertilizer to Reduce PhosphorusLosses and Maximize ReturnsApplying P fertilizer at rates higher than production requirementsis unwise from both environmental and economicviewpoints. Today, there is no agronomic justification forbuilding P soil test levels higher than crop sufficiency levels.Phosphorus losses in surface runoff have been shown toincrease with increased P application rates. Therefore, oncethe 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 ofP available for transport to surface water. Correct placementof fertilizers in the plant root zone will improve fertilizer useefficiency and seedling vigor, and reduce the amount of Pin agricultural runoff. Phosphorus fertilizer should not bebroadcast on the soil surface without incorporation, excepton perennial forages. In established alfalfa stands, P fertilizernormally should not be applied in the late fall or winter whengrowth is minimal and runoff potential is high. Broadcastapplications generally are less efficient and leave more P atthe soil surface than banding (Figure 2). Band application atplanting is considered the most efficient method for manycrops. Subsurface placement is especially important underreduced tillage cropping systems to achieve maximum cropyields.Variable fertilizer rate management can improve bothfertilizer use efficiency and economic returns. While thisstrategy can be adopted for any fertilized field, it makes themost sense in relatively large fields where the producer hasknowledge of how crop yields and soil type vary across thefield. To use a variable fertilizer rate strategy:1. Divide the field into different management units basedupon 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 yieldcapability.Field maps should be modified at harvest as necessaryto refine the boundaries of management units. Consult withyour fertilizer dealer or crop advisor prior to adopting thisBMP.Sumber: Diunduh 17/3/2012
130Managing Manure to Reduce COLORADO STATE UNIVERSITY EXTENSIONBulletin #XCM-175Reagan M. Waskom and Troy BauderManaging Manure to ReducePhosphorus LossesManure is an excellent source of P for crop production.However, if manure is not incorporated into the soil, runoffmay carry both soluble and sediment-associated nutrients tosurface waters. The most common strategies for manure utilizationare (1) application for maximum nutrient efficiencyand (2) application for maximum disposal rates of manure.While the second strategy presents a more difficult challengefrom a water quality viewpoint, both management methodsshould consider application rates, timing, site characteristics,and water quality impacts.Manure managed for maximum nutrient efficiencyis the most sound manure application program. Producersneed soil and manure analyses to determine the correct applicationrate based upon crop uptake of N and P. Either ofthese nutrients may limit application rate, as both nutrientsare present in large quantities in manures. In many cases, thebest program is to rotate fields receiving manures to avoidsalt or nutrient buildup.Colorado producers faced with the need for manuredisposal at maximum application rates should have manuresanalyzed for nutrient content and apply according to crop nitrogenneeds. However, this strategy may lead to an accumulationof P over long-term, repeated applications. Therefore,it is essential that producers manage water on their fieldcarefully, minimizing runoff and leaching. Poultry manurecontains exceptionally high levels of P and should be appliedat rates based upon crop P removal. Annual soil tests arestrongly recommended on all fields receiving manure. Operatorsshould rotate manure applications when soil tests shownutrient levels greater than, or sufficient for, crop needs.Sumber: Diunduh 17/3/2012
131COLORADO STATE UNIVERSITY EXTENSION Bulletin #XCM-175 Reagan M. Waskom and Troy BauderThe 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 beevaluated using the COPI to determine risk of P loss andmanagement changes that could lower this risk.As with commercial P fertilizers, manure should be incorporatedimmediately after application. Injection of liquidmanure beneath the soil surface with specialized equipmentis also a recommended practice. Unlike commercial fertilizer,the P content of manure can vary significantly. Approximatevalues are available for various manure sources (Table 2), butmanure sampling and analysis are the best way to calculatenutrient credit.Table 2. Approximate P content of various manures1 whenapplied to land (wet weight basis)Sumber: Diunduh 17/3/2012
132Managing Soil to Reduce Phosphorus Losses COLORADO STATE UNIVERSITY EXTENSIONBulletin #XCM-175Reagan M. Waskom and Troy BauderManaging Soil to Reduce Phosphorus LossesAlthough there are a number of sources of sediment enteringour waters, soil erosion from agricultural fields is a significantcontributor to nonpoint source pollution in Colorado.The consequences of cropland erosion include loss of fertiletopsoil, eutrophication and sedimentation of surface waters,destruction of habitat, and decreased recreational and aestheticvalue of lakes and streams. Runoff from agriculturalland also can transport pesticides and microbial pathogens,as well as nutrients.Owners of agricultural land should contact the NaturalResources Conservation Service (NRCS) for help in evaluatingthe erosion potential of their lands and in determiningwhat control measures are needed. In some cases, the NRCShas cost-share funds available to help producers install BMPson their land.A number of management practices and structures forcontrolling runoff and erosion are currently available for use.In some cases, there is a trade-off between reducing runoffand increasing deep percolation to groundwater. BMPs formanaging surface runoff and soil erosion are listed in Table 3.Sumber: Diunduh 17/3/2012
133COLORADO STATE UNIVERSITY EXTENSION Bulletin #XCM-175 Reagan M. Waskom and Troy BauderTable 3. Erosion control BMPs for reducing surface losses of phosphorus from crop fieldsSumber: Diunduh 17/3/2012
134COLORADO STATE UNIVERSITY EXTENSION Bulletin #XCM-175 Reagan M. Waskom and Troy BauderPhosphorus BMPs4.1 Sample the tillage layer of soil in each field on a regularbasis and have soil analyzed to determine available soil Plevels prior to applying P fertilizer.4.2 Credit all available P from manures and other organicresidues to the P requirement for the crop.4.3 Fertilize soils with ‘low’ to ‘medium’ P soil test valuesusing environmentally and economically sound agronomicguidelines. In general, soils testing ‘high’ will notrespond to additional P and should not receive fertilizerunless a banded starter is needed to compensate for lowsoil temperatures. Phosphorus fertilizer should not beapplied to soils testing ‘very high’ for soil P.4.4 Divide large, non-uniform fields into smaller fertilitymanagement units based upon yield potential orsoil type and fertilize according to P levels determinedthrough soil analysis.4.5 Apply P fertilizers where they can be most efficientlytaken up by the crop. Band application of P in the rootzone reduces surface loss potential and enhances nutrientavailability, especially in cold or P deficient soils.4.6 Incorporate surface applied P into the soil where anypotential for surface runoff or erosion exists.4.7 Minimize soil erosion and corresponding P losses byestablishing permanent vegetative cover, conservationtillage and residue management, contour farming, stripcropping, and other management practices as feasible.When erosion potential is severe, install structures suchas diversions, terraces, grass waterways, filter fences,and sediment basins. Contact your local NRCS office ifyou need assistance in evaluating erosion potential andcontrol options.4.8 Maintain a buffer strip (where fertilizer and manureis not applied) a safe distance from surface water anddrainage channels.4.9 Maintain grass filter strips on the downhill perimeter oferosive crop fields to catch and filter P in surface runoff.4.10 Manage irrigation water to minimize runoff and erosionby meeting the Irrigation BMPs or the NRCS approvedIrrigation Water Management practice standard andspecification.4.11 Evaluate fields with historical manure applications usingthe Colorado Phosphorus Index Risk Assessment.Sumber: Diunduh 17/3/2012
135The phosphorus cycle in agricultural soils. COLORADO STATE UNIVERSITY EXTENSIONBulletin #XCM-175Reagan M. Waskom and Troy BauderThe phosphorus cycle in agricultural soils.Phosphorus placement influences the amount availablefor transport. Band placement of P fertilizers is recommendedfor erosive soils.Sumber: Diunduh 17/3/2012