micronutrient deficiencies in wheat kurt steinke, ph.d. soil fertility & nutrient mgmt. dept. of...
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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)
K. Steinke, MSU
Micronutrient Use is Increasing Because of:
Higher crop yieldsWidespread use of N-P-K fertilizersHigher analysis fertilizers containing less micronutrientsSales gimmick ($$)
K. Steinke, MSU
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
K. Steinke, MSU
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
K. Steinke, MSU
Yellow, stunted necrosis along edges
K. Steinke, MSU
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
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