Micronutrient Deficiencies in Wheat

Kurt Steinke, Ph.D.Soil Fertility & Nutrient Mgmt.

Dept. of Plant, Soil, and Microbial Sciences

Michigan State University

General Comments on Micronutrients

Micronutrients defined as:Nutrients required by a plant for growthAmount needed is very small (<100 mg/kg) compared to macronutrients (primary & secondary)Deficiency can be just as yield limiting as a deficiency of a macronutrient

K. Steinke, MSU

The Eight Micronutrients

Boron (B)Chloride (Cl)Copper (Cu)Iron (Fe)

Manganese (Mn)Molybdenum (Mo)Nickel (Ni)Zinc (Zn)

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Micronutrient Use is Increasing Because of:

Higher crop yieldsWidespread use of N-P-K fertilizersHigher analysis fertilizers containing less micronutrientsSales gimmick ($$)

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Soil pH Has the Greatest Impact on Nutrient Use Efficiency

4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 extreme strong slight acidity acidity acidity slight alkalinity

strong alkalinitynitrogen

phosphorus

potassium

sulfur

calcium

magnesium

iron

molybdenum

manganese

copper and zinc

boron

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Micronutrients - MnHealthy leaves: 40 – 100 ppm Mn (40-60 target)

Conc. decreases as season progresses< 20 ppm: deficient

Immobile in plantYoung leaves affected (shadow effect)

Interveinal chlorosis (many field crops)Wheat: Yellow, dis-colored, colorless spots (Similar to disease)

Causes: high soil pH (>6.5), imbalance with other nutrients (Ca, Mg, Fe, Zn)

For every 1 pH unit ↑, 100x decrease in soil [Mn2+]

K. Steinke, MSU

K. Steinke, MSU

Micronutrients - Mn

Corrective MeasuresMost effective as starter applicationsSoil or foliar

Soil banded: 4 – 18 lbs Mn/A (Mn sulfate)Soil b-cast: >20 lbs Mn/A (not recommended)

Mn oxides and chelates not effective for soil application

Foliar: 1-2.5 lb Mn/A in 30 gal H2O

Mn sulfate or chelates work bestDo not apply to chelate to soil as other cations (e.g., Ca or Fe) often replace Mn in the chelate and convert to unavailable forms

K. Steinke, MSU

Micronutrients - CuHealthy leaves: 8 – 50 ppm Cu (target 8-20 ppm)

Conc. often increases as season progresses (incr root area)< 6 ppm: deficient

Immobile in plantYoung leaves affected (shadow effect)

Wilting, lack or turgor, bluish-green tipOften confused with disease symptoms

Grain loses pigmentationEventually chlorotic leaf tips and death (may be confused with cold damage)

Causes: Peaty/muck soils, imbalance with other nutrients (Zn, P, Fe

Rare on most Michigan mineral soilsWhere present: acid soils, heavily cropped with N, P, and K

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Yellow, stunted necrosis along edges

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Micronutrients - CuCorrective Measures

Soil or foliarSoil: 1 – 20 lbs Cu/A based on soil test (Cu sulfate or oxide)

Muck/Peat: 20-40 lb/A for low or high responsive cropChelates not effective for soil application

Foliar: 0.5 – 1.0 lb Cu/A in 30 gal H2O

Cu sulfate or chelates work bestDo not apply chelate to soil as other cations (e.g., Ca or Fe) often replace Cu in the chelate and convert to unavailable forms

Beware: Cu doesn’t leach; If apply too much, toxicity problems are difficult to correct

K. Steinke, MSU

Take Home PointsTissue Deficiencies

Something will be deficient at some point in the season

Does NOT equate to yield-limiting factor

Collect BOTH soil and plant tissueCollect from good AND poor areas

Good area = reference pointTransitional area may be sampled to determine why issue occurred

Some is good, more is not betterBeware of large bulk nutrient application

Cation/anion interferenceEx. : High Ca interfering with Mn Are you creating your own problem?

K. Steinke, MSU

Thank You for the Support!

K. Steinke, MSU