Plant Nutrition January 2008 Andrew G. Ristvey

Plant Nutrition January 2008 Andrew G. Ristvey
Wye Research and Education Center Maryland Cooperative Extension College of Agriculture and Natural Resources University of Maryland

Master Gardener Program
Plant Nutrition Master Gardener Program Objectives for this topic include: * The essential macro and micronutrients necessary for plant growth and the basic mechanisms for availability and uptake of nutrients. * Organic and inorganic fertilizers and how they are used by the plant. * The negative effects of over-applied or mis-applied fertilizers. * Appropriate timing of fertilizer application and fertilization for special situations

Growth Factors: What do plants need to grow?
1. 2. 3. 4. 5. 6. Light Water Temp O2 Co2 Nutrients

What is an essential plant nutrient?
All the nutrients needed to carry out growth and reproductive success; full life cycle The criteria for essentiality: Arnon and Stout, 1939 Omission of the element will result in abnormal growth The element cannot be replaced or substituted The element must exert its effect directly on growth

There are 17 known (accepted) elements that are essential for plant growth Hydrogen, Oxygen, Carbon – plant gets from air and water The other 14 are mineralized elements derived from soil (or air as in N) Other nutrients being studied: Silicon, Cobalt, Aluminum

Relationship between plant growth and nutrient concentration
What happens when a nutrient or nutrients are inadequate in supply? Can the concentration of a nutrient be too high?

von Liebeg’s ‘Law of the Minimum’ Plant growth progresses to the limit imposed by the nutrient in least supply

von Liebeg’s ‘Law of the Minimum’ Plant growth progresses to the limit imposed by the nutrient in least supply tires chassis engines

Nutrient % ppm Nickel 0.05? Macronutrients Micronutrients Nitrogen 1.5
Potassium 1.0 Calcium 0.5 Magnesium 0.2 Phosphorus Sulfur 0.1 Chlorine 100 Iron Manganese 50 Boron 20 Zinc Copper 6 Molybdenum Nickel 0.05? Macronutrients Micronutrients

Forms in which nutrients exist
cation – positively charged ion anion – negatively charged ion neutral – uncharged Plants used the mineralized from of a nutrient It does not matter to the plant where it comes from

So which nutrients exist in what form?
Cations Anions ammonium – NH4+ potassium – K+ calcium – Ca+2 magnesium – Mg+2 iron – Fe+2, Fe+3 zinc - Zn+2 manganese Mn+2, Mn+4 copper – Cu+2 cobalt – Co+2 nickel – Ni +2 nitrate – NO3- phosphate – H2PO4- , HPO4-2 sulfate - SO4-2 chlorine – Cl- borate - H3BO3, H2BO3-, B4O7-2 molybdate – MoO4-2

Factors that affect nutrient uptake
Getting nutrients to the plant roots Nutrients are water soluble What factors affect nutrient availability pH Cation Exchange Capacity Colloids (humus, clay)

Getting nutrients to the roots: Mechanisms for nutrient delivery
mass flow the passive movement of nutrients in soil water to roots diffusion the movement of nutrient from regions of high concentration to regions of low concentration root interception direct contact of nutrients with roots as roots grow and explore soil

Getting nutrient to the roots: Mechanisms for nutrient delivery

Properties Affecting Nutrient Availability
Chemical Properties - pH p = potential or power H = hydrogen pH and hydrogen ion concentration are inversely related. As pH increases, hydrogen ion concentration decreases. I would think of your audience with this slide – do they know or care that pH and H ion concentration are inversely related, or that H ion concentration decreases as pH increases? …. Keep it relatively simple I think.

Chemical Properties - pH pH [H+] 1 10-1 .1 2 10-2 .01 3 10-3 .001 4 10-4 .0001 5 10-5 .00001 6 10-6 7 10-7 8 10-8 9 10-9 Logarithmic scale pH of 6 has 10x more H+ than pH 7 I would think of your audience with this slide – do they know or care that pH and H ion concentration are inversely related, or that H ion concentration decreases as pH increases? …. Keep it relatively simple I think.

Chemical Properties - pH pH affects the availability of nutrients

Chemical Properties – Cation Exchange Capacity C E C Cations Anions ammonium – NH4+ potassium – K+ calcium – Ca+2 magnesium – Mg+2 iron – Fe+2, Fe+3 zinc - Zn+2 manganese Mn+2, Mn+4 copper – Cu+2 cobalt – Co+2 nickel – Ni+2 nitrate – NO3- phosphate – H2PO4-HPO4-2 sulfate - SO4-2 chlorine – Cl- borate - H3BO3, H2BO3-, B4O7-2 molybdate – MoO4-2

Growing Media - Chemical Properties
Chemical Properties - pH pH affects the availability of nutrients Negatively charged chemical groups OH- on humic particles Sometimes associated with Fe and Al in clays H+ OH- pH High or Low ? OH- A very low or a very high pH can kill roots. pH affects the availability of nutrients OH- Low OH- OH-

Chemical Properties - pH pH affects the availability of nutrients Negatively charged chemical groups OH- on humic particles Sometimes associated with Fe and Al in clays H+ OH- pH High or Low ? OH- A very low or a very high pH can kill roots. pH affects the availability of nutrients OH- High OH- OH-

Chemical Properties – Cation Exchange Capacity C E C The ability of a soil or substrate to provide a nutrient reserve It is all the exchangeable cations the soil or substrate can adsorb The CEC of a soil depends on colloids and pH The higher the CEC of a soil the better buffering capacity

Chemical Properties – Colloids and CEC Colloids - very small particles in soil that are chemically reactive (charged) – humus, clay + attracts Fe++ Fe++ Mg++ K+ H+ H+ H+ Ca++ Mg++ Mg++ K+ Mn++ Mn++

Chemical Properties - Colloids and CEC pH affects the availability of nutrients Example of one scneario: some nutrients become more available at low pH Mg++ Fe++ Mn++ OH- Ca++ OH- Fe++ A very low or a very high pH can kill roots. pH affects the availability of nutrients Mn++ Fe++ OH- Mn++ Mg++ Fe++ OH- OH- Mn++ Fe++

Chemical Properties – CEC pH affects the availability of nutrients H+ ions vie for space, certain ions released becoming available Mn++ H+ Fe++ Mn++ pH ≈ 5.8 Ca++ OH- Fe++ OH- A very low or a very high pH can kill roots. pH affects the availability of nutrients and slightly low pH Iron and Al compete with Ca at low pH In soilless substrates Ca availalbity is not affected by pH Mn++ OH- Mn++ Fe++ Ca++ OH- OH- Mn++ Mn++ Fe++

Cation Exchange Capacity
Properties Affecting Nutrient Availability Chemical Properties – Cation Exchange Capacity C E C The ability of a soil or substrate to provide a nutrient reserve Cation Exchange Capacity (cmolc/kg of colloid) Types of Soil Colloids humus vermiculite montmorillonite 60-120 illite 15-40 0-3* iron oxides

What’s on the Bag N P K 10 – 10 – 10 # - # - # N – P2O5 – K2O 1.00 –
0.44 – 0.83 N – P – K

The Major Players – N and P
Nitrogen NO3- N and NH4+-N or urea Phosphorus H2PO4--P at pH of 5.0 to 6.5 Two forms of nitrogen is utilized by plants nitrate and ammonium or urea Nitrate is taken up by plants passively and actively. Assimilation increases pH in soil. Best uptake pH range between 4.5 and 6. It can be stored. Ammonium assimilation in both leaves and roots. Assimilation lowers soil pH. Ammonium is quickly converted to ammonia – very toxic – must be made into amino acids immediately uses up carbon. Because of pH interactions the best fertilizer has a mix of both, Ericaceous species need more ammonium. Nitrate form leaches. Phosphorus is taken up at H2PO4- (dihydrogen form of the orthophosphate) which is the predominant form of P in the soil at pH between 5.0 and 6.5

Nitrogen (N) NO3- N and NH4+-N or urea
utilized for a variety of structural and metabolic compounds over half of N in plants is found in the leaves of plants between 15 and 30% of that leaf nitrogen goes into the production of Ribulose 1-5-biphosphate carboxylase or Rubisco Nitrogen is very mobile within the plant Rubisco - the most abundant enzyme on earth and the key plant enzyme that facilitates the production of carbohydrates from carbon dioxide (Evans

Nitrogen (N) NO3- nitrate taken up by plants passively and actively
uptake increases pH in soil best uptake pH range between 4.5 and 6 nitrate can be stored in plant nitrates leach

Nitrogen (N) NH4+ ammonium taken up by plants passively and actively
decreases pH in soil ammonium (ammonia) cannot be stored must be assimilated immediately by carbon ericaceous species utilize Two forms of nitrogen is utilized by plants nitrate and ammonium or urea Nitrate is taken up by plants passively and actively. Assimilation increases pH in soil. Best uptake pH range between 4.5 and 6. It can be stored. Ammonium assimilation in both leaves and roots. Assimilation lowers soil pH. Ammonium is quickly converted to ammonia – very toxic – must be made into amino acids immediately uses up carbon. Because of pH interactions the best fertilizer has a mix of both, Ericaceous species need more ammonium. Nitrate form leaches. Phosphorus is taken up at H2PO4- (dihydrogen form of the orthophosphate) which is the predominant form of P in the soil at pH between 5.0 and 6.5

Phosphorus (P) H2PO4- -P at pH of 5.0 to 6.5
High pH, P binds with calcium Low pH P, binds with iron High P fertilizers do not promote root growth Utilized for energy transfer, membrane structure, nucleic acids, proteins Rubisco - the most abundant enzyme on earth and the key plant enzyme that facilitates the production of carbohydrates from carbon dioxide (Evans Mobile in plant

Nutrient Interactions: Relationships of elemental excess
in growing media to potential nutrient deficiencies in plant tissue. Element in excess in media Element possibly deficient in plant tissue Nitrogen as ammonium Potassium, Calcium, Magnesium Potassium Nitrogen, Calcium, Magnesium Phosphorus Copper, Zinc, Iron Calcium Magnesium, Boron Magnesium Calcium, Potassium Sodium Manganese Iron, Molybdenum Iron Zinc Manganese, Iron Copper Manganese, Iron, Molybdenum Molybdenum Aluminum: this element is not essential and high levels are rare in artificial soils. High Aluminum will precipitate Phosphorus as Aluminum Phosphate and can highly reduce short term Phosphorus availability.

Mobility of Plant Nutrients: Mobility of elements in the Very Mobile
plant often defines the location of visual symptoms of nutrient deficiencies or toxicities: Very Mobile Moderately Limited Mobility Nitrogen Magnesium Iron Phosphorus Sulfur Manganese Potassium Molybdenum Copper Chlorine Zinc Calcium Boron * Most recently matured leaves are the most accurate leaf sample for nutrient analysis.

Nutrient Form: Organic or Inorganic?
Plants used the mineralized form of a nutrient It does not matter to the plant where the nutrient comes from, as all nutrients taken up are in a mineralized form See handout on types of organic and inorganic fertilizers However adding composted organic matter to your soil will aid in nutrient availability See lesson on soils

Nutrient Form: Composts and Teas?
Composts are denatured organic materials A true aerobic compost requires 3 things Aeration Moisture – 40 to 60 % A C:N ratio of 30 to 1 Anaerobic composting – less heat, more break down, increased humus production, but more noxious gases Compost present many attributes, not to mention the ability to deal with yard, kitchen and other organic wastes that would otherwise be placed in a landfill. Aeration increases aerobic microbial activity and faster composting. Prevent anaerobic processes which can create alcohols, ammonia methane and other noxious compounds like hydrogen sulfide Anaerobic composting is a reducing process so humus is generated. Less heat is gnerated. The heat energy resides in the methane. Moisture should be between 40 and 60% Making teas from composts is easy, however making a consistent product is not Anti-pathogen properties

Foliar Nutrient Application
Plants use the mineralized form of a nutrient The majority of nutrient uptake are via plant roots Nutrients can be applied via foliar application Foliar application should merely be supplemental For most nutrients If foliar application is the primary method of nutrition something is wrong with your soil ! (or roots)

Other Negative Effects of Nutrient Over-application
Runoff Physiological responses may affect root growth e.g. recent evidence shows P does not promote root growth may affect flowering e.g. over application of N and other nutrients may stimulate vegetative growth as in grapes Inappropriate fertilizers NO3 is not well utilized by ericaceous species Balance your NO3 with your NH4 good for most plants

Timing of Fertility Evidence of periodicity in nutrient uptake in some species evidence for opposite shoot growth/root uptake periods fall uptake for spring growth Lawn care specialists suggest fall fertilization Arborist stress fall fertilization of trees and shrubs Tree nursery recommendations stress split fertilization early spring and mid summer Some concern over cold hardiness issues with fall N fertility

Fertility - special situations
Drought fertility Water is the most important growth regulator No water, no growth regardless nutrients Fertilizing under drought conditions is not recommended High EC’s in soil can damage roots New Plantings Recent recommendation discourage fertility with new plantings ? What condition (nutrient reserve) were the plants in at purchase Watering is more important

Suggested Readings Growing Media for Ornamental Plants and Turf.
Handrek, K and N. Black. Uni. of New South Wales Press ISBN

Where does the Nitrogen go ?
13 g N Drip 63% ? Both Liquid and CRF 13% Plant 15% Runoff Plant Uptake Efficiency 21% 8% Pruning 1% Substrate holly data, 2001

Plant Uptake Efficiency
Where does the Nitrogen go ? Overhead Irrigation 33 g N Both CRF and Liquid Feed ? 69% 5% Plant 3% Pruning Andrew, I’m concerned that you are going to lose the audience with this and the next two slides – they are very (too?) detailed and I think they may miss the point…. I’ve edited this slide as a simplified example….. 22% Runoff 1% Substrate Plant Uptake Efficiency 8% Take home message – great microbial competitiion for N Holly data, 2001

Fertility - special situations
Mycorrhizal Symbiosis Fungal infection creates a mutualistic relationship with plant Ectomycorrhizal and Endomycorrhizal (more common) Very useful to the plant under conditions of low fertility High fertility retards rate of infection Fungal mycelia are smaller, have greater surface area than plant roots Potential disease resistance, drought resistance via symbiosis Mycorrihzae take C compounds from plant… initially slows growth … eventual long term benefits

N Fertility Recommendations (Turf)
N Fertilizer plan considerations what types of N should be applied annual N application rates application timing Application Rate and Timing – one application, two or three applications Seasonal application – evidence shows seasonal uptake of nutrients in woodies -

N Fertility Recommendations (Turf)
N Fertilizer - types All soluble or mixed with slowly available nitrate, ammonium or both turf uses mainly nitrate (NO3) nitrate taken up within 3 days of application leaching potential high for nitrate should not use in areas that are leaching prone should use a 50% WIN formula Application Rate and Timing – one application, two or three applications Seasonal application – evidence shows seasonal uptake of nutrients in woodies -

N Fertility Turf Recommendations
N Fertilizer – rate issues how much to apply per application how much to apply per year N Fertilizer Recommendations all soluble – no more than 1 lbs per 1000 sq.ft Application Rate and Timing – one application, two or three applications Seasonal application – evidence shows seasonal uptake of nutrients in woodies - nitrate, ammonium or both can increase rate if you have S.R. N, but only up to the annual max rate

Years 1-2 Subsequent Years Cool Season Grasses Kentucky bluegrasses Turf-type tall fescue Fine fescue Perennial Ryegrass Warm Season Grasses Bermudagrass Zoysiagrass Application Rate and Timing – one application, two or three applications Seasonal application – evidence shows seasonal uptake of nutrients in woodies - Table 1. Nitrogen Recommendations for Commercially Maintained Turfgrass on Sites Total Nitrogen Annually (lbs. N/1000 ft2) adjust if mulching or in low traffic areas

Recommended Periods Periods to Avoid Warm Season Grasses 1 month before dormancy breaks through Sept. 1st September 1st through 1 month before dormancy breaks During severe or prolonged drought Cool Season Grasses 1 month before top growth starts through early June Late August through 6 weeks after first killing frost Mid-June through mid-August When turf is dormant due to heat, drought, or cold * Dormancy generally breaks in mid-April in Central MD (later in Western MD and earlier in Eastern MD) **Topgrowth generally begins in late March in Central MD (later in Western MD and earlier in Eastern MD) Table 2. Recommended Periods for N Fertilization of Turf Areas.

P Fertility Turf Recommendations
P Fertilizer – rate issues Unlike N, based on soil test results P is not needed in large quantities P Fertilizer Recommendations before soil test results no more than 1 lbs P2O5 per 1000 sq.ft

Soil Testing Performed at least every 3 years
the analysis is as good as the sample useful tool, different extraction methods in Maryland, test results converted to FIV Low, Medium, Optimum - Excessive Calculating the right amount gauge P and K fertility on these values

FIV Soil Test Category lbs of P2O5 per 1000 sq/ft Low 0-25 Medium Optimum - Excessive 51-100, >100 2.0 1.0 0.0 Application Rate and Timing – one application, two or three applications Seasonal application – evidence shows seasonal uptake of nutrients in woodies - Table 3. Phosphate Recommendations for Maintenance of Turf Sites Based on FIV Soil Test Results

Soil Testing Performed at least every 3 years Sampling
the analysis is as good as the sample Sampling divide area into similar soils, slopes, history scrape surface litter, sample 4 inches down Calculating the right amount take at least 15 random cores mix samples in clean bucket fill sample bag 1/3 to 1/2 full

Soil Testing Interpreting analysis Conversion to FIV
Converting lab values to FIV Conversion to FIV conversion depends on Lab each lab has its own analysis one value (FIV) is needed for fertility recommendations Calculating the right amount

Soil Testing Phosphorus, Bray P1 29 ppm
To determine an equivalent Maryland FIV value for each soil-test nutrient, multiply the regional laboratory reported value, expressed in the units shown, by the value in column A and then add the value in column B. Example: A soil-test report from A & L Laboratories contains the following data: Phosphorus, Bray P1 29 ppm

86 ppm P-FIV (86 x 1.69) + 6 = 151

FIV Soil Test Category lbs of P2O5 per 1000 sq/ft Low 0-25 Medium Optimum - Excessive 51-100, >100 2.0 1.0 0.0 55 151 Table 3. Phosphate Recommendations for Maintenance of Turf Sites Based on FIV Soil Test Results

Nitrogen (N) Symptoms of Deficiency and Toxicity Deficiency
- occurs in oldest leaves first - stunted growth yellowing, chlorosis, stunted growth, leaf drop, increased root shoot ratio Toxicity - occurs with ammonium only - yellowing, chlorosis, root death - interactions with K, Ca, Mg

Phosphorus (P) Symptoms of Deficiency and Toxicity Deficiency
- occurs in oldest leaves first - older leaves darken and turn purple, leaf margin necrosis, low production of flowers, fruit and seed Toxicity - mostly interactions with other nutrients including zinc, copper and iron

Potassium (K) K+ Like phosphorus, potassium exists as many forms in soils, and much of it is unavailable to plants, Plants take up potassium in large amounts compared to other nutrients. Only the demand for nitrogen is greater. In plant tissue the N:K ratio is close to 1:1. Maintains a variety of plant metabolic activity mainly by regulating water status and stomatal control. Rubisco - the most abundant enzyme on earth and the key plant enzyme that facilitates the production of carbohydrates from carbon dioxide (Evans Aides in carbohydrate transport and cellulose production. Mobile in plant

Potassium (K) Symptoms of Deficiency and Toxicity Deficiency
- occurs in oldest leaves first - yellowing of margins and tips of leaves - edge “scorch” Toxicity - mostly interactions with other nutrients including calcium and magnesium

Sulfer (S) SO4-2 In soil, the majority of sulfur is found in organic form and to a lesser extent mineral form as sulfates Plant roots actively take up sulfur primarily as sulfates SO4 -2, Plants utilize sulfur in amino acids, proteins, vitamins and other plant compounds like glycoside oils that give onions and mustards their characteristic flavors.. Rubisco - the most abundant enzyme on earth and the key plant enzyme that facilitates the production of carbohydrates from carbon dioxide (Evans Sulfur also activates certain enzyme systems Not Mobile in plant

Sulfur (S) Symptoms of Deficiency and Toxicity Deficiency
- occurs in youngest leaves first - similar to N deficiency Toxicity - There are rarely issues of toxicity

Calcium (Ca) Ca 2+ Free calcium is loosely bound to organic and mineral colloids Calcium is taken up passively in roots tips and moves through the plant primarily via the xylem during evapotranspiration Mainly found in the cell walls Calcium is required for the extension of cell walls during cell growth at shoot and root tips and enhances pollen tube growth. Rubisco - the most abundant enzyme on earth and the key plant enzyme that facilitates the production of carbohydrates from carbon dioxide (Evans Responsible for membrane stability and cell wall integrity Not Mobile in plant

Calcium (Ca) Symptoms of Deficiency and Toxicity Deficiency
- Occurs in youngest leaves first - Reduction of growth at meristems - Deformed and chlorotic leaves - leag margin necrosis Toxicity - mostly interactions with other nutrients including magnesium, potassium causing deficiencies

Magnesium (Mg) Mg 2+ Magnesium is made available to the plant through exchange with soil colloid complexes Plants take-up magnesium passively, transported mainly through the phloem Fifteen to twenty percent of the magnesium in plants is found in the pigment molecule, chlorophyll. Rubisco - the most abundant enzyme on earth and the key plant enzyme that facilitates the production of carbohydrates from carbon dioxide (Evans Cofactor for enzymes that help transfer energy and CO2 fixation Assists in RNA translation for protein synthesis Mobile in plant

Magnesium (Mg) Symptoms of Deficiency and Toxicity Deficiency
- Deficiency symptoms appear in older leaves as interveinal chlorosis. Toxicity - There is typically no magnesium toxicity.

Chlorine (Cl) Cl - Chlorine naturally occurs in soils as constituents of many soil minerals and is made available through natural weathering. Taken actively and passively depending on soil concentrations, active when low and passive when concentrations are high Utilized in several processes of photosynthesis. Rubisco - the most abundant enzyme on earth and the key plant enzyme that facilitates the production of carbohydrates from carbon dioxide (Evans Mobile in plant

Chlorine (Cl) Symptoms of Deficiency and Toxicity Deficiency
- Deficiencies are uncommon Toxicity Yellowing and burning of leaf tips, with interveinal areas being bleached, scorched and necrotic in severe cases.

Iron (Fe) Fe 2+ Iron is ubiquitous in many soils, yet availability depends on soil chemistry. Actively taken up by the plant and is transported by xylem to the leaves. Utilized in several processes of photosynthesis. Rubisco - the most abundant enzyme on earth and the key plant enzyme that facilitates the production of carbohydrates from carbon dioxide (Evans Not mobile in plant

Iron (Fe) Symptoms of Deficiency and Toxicity Deficiency
- Iron deficiency is similar to magnesium deficiency symptoms (interveinal chlorosis), but occurs on youngest leaves first Toxicity - iron interferes with manganese uptake manganese deficiency (mottled yellowing between veins developing as necrotic lesions later), as.

Manganese (Mn) Mn 2+ Availability depends on pH and organic colloid content. Increased in low pH In the plant manganese is transported in the xylem and delivered to mertistematic tissue where it is largely immobilized. Cofactor for many metabolic enzymes and is important factor in photosynthesis. Used to split water. Not mobile in plant

Manganese (Mn) Symptoms of Deficiency and Toxicity Deficiency
- Interveinal chlorosis, similar to iron and zinc. Toxicity - Toxicity varies among species. - Occurs in acid soil conditions when manganese is most available - Dark purple or brown spots within the leaf margins and/or leaf tip necrosis - Toxicity varies among species. Plants associated with acid soils are naturally tolerant to high manganese conc. - Severe toxicity results in stunted and yellowed meristems.

Boron (B) H3BO3 Availability depends on pH and organic colloid content. Increased in low pH Boron moves into the plant, passively taken up in solution by the roots via evapotranspiration, moving through xylem Factor in cell growth, including division, differentiation, and elongation Cell processes like carbohydrate metabolism and other metabolic pathways Concentrated at growth areas including reproductive structures. Not mobile in plant

Boron (B) Symptoms of Deficiency and Toxicity Deficiency
- Since boron is associated with cell growth, deficiencies usually show up in new growth as wrinkled and withered leaves, with tip death soon after. - Like calcium, deficiencies may be caused by drought or high humidity. Toxicity - Toxicity can develop quickly, the range between deficient and toxic supply is small. - Different tolerances among plant species. - Yellowing of the leaf tips, interveinal chlorosis and leaf margin scorching.

Copper (Cu) Cu 2+ Optimally available in slightly acid conditions where the copper ion exchanges with other cations on soil colloids Root uptake is active and copper moves in the xylem, complexed with amino acids and other nitrogenous compounds. Copper is utilized with enzymes for metabolic activities and photosynthesis. Not mobile in plant

Copper (Cu) Symptoms of Deficiency and Toxicity Deficiency
- Deficiencies of copper show up on the youngest leaves first - Depressed and twisted growth - New leaves appear pale along the margins but green at the end of the veins. - Spotty necrosis occurs in the leaf margins. Stems may become distorted and twisted. Toxicity - Toxic levels of cooper induce iron deficiency and accompanying symptoms along with depressed root growth.

Molybdenum (Mo) MoO4 -2 Molydenum uptake is dependent on solubility of the ion. Unlike many micronutrients, molybdenum becomes more available in higher pH. In the leaf, used for an important enzymatic process called nitrate reduction, the first of two important physiological steps that make nitrate usable in the plant Relatively mobile in plant

Molybdenum (Mo) Symptoms of Deficiency and Toxicity Deficiency
- Since molybdenum is essential for nitrate reduction, a deficiency in molybdenum manifests as a nitrogen deficiency - leaf chlorosis in older leaves - then leaf margin wilting - leaf and meristem death Toxicity - rare in soils and plants can tolerate relatively high levels of molybdenum

Zinc (Zn) Zn +2 present in sulfide and silicate minerals and is also associated with organic colloids Zinc is actively taken up by plants and transported through the xylem metabolic functions including auxin (growth hormone) production, a cofactor in protein synthesis, enzyme activity and carbohydrate metabolism and regulation. chlorophyll production may enable plants to tolerate colder temperatures Slightly mobile in plant, mainly stored in roots

Zinc (Zn) Symptoms of Deficiency and Toxicity Deficiency
- Symptoms on older leaves first - Include interveinal chlorosis, curled and dwarfed leaves and then leaf scorch and necrosis. - excessive phosphorus can interfere with zinc uptake Toxicity - May occur in low pH soils (< pH 5) or where municipal sludge has been added to soils - Toxicity concentrations are species dependent - interfere with iron uptake

Nickel (Ni) Ni +2 Nickel is the newest recognized essential plant nutrient requirement was not known because impurities in irrigation water and fertilizers supplied the very low requirements of this nutrient required for the enzyme urease to metabolize urea, releasing the ammoniacal nitrogen for plant use for iron absorption and seeds production and germination evidence to suggest that carbon respiration and nitrogen metabolism are sensitive to Ni nutrition Possibly mobile in plants

Nickel (Ni) Symptoms of Deficiency and Toxicity Deficiency
- rounded, blunt and slightly curled leaves known as “mouse-ear” - seen on spring growth and is a result of accumulation of urea to the point of toxicity Toxicity - At a level of 100 ppm or higher, nickel is considered to be phytotoxic - toxicities typically exist in areas where industrial waste has been concentrate - In beets severely stunted growth; young leaves at early stage show chlorotic iron deficiency symptoms, followed by severe necrosis, collapse and death

Plant Nutrition January 2008 Andrew G. Ristvey

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