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Secondary and Micronutrient Management

Secondary and Micronutrient Management. Kent Martin Southwest Area Crops and Soils Specialist Kansas State Univ. Essential Nutrients. Thirteen essential nutrients Nitrogen, phosphorus, potassium, calcium, magnesium, sulfur Iron, manganese, boron, molybdenum, copper, zinc, and chlorine

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Secondary and Micronutrient Management

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  1. Secondary and Micronutrient Management Kent Martin Southwest Area Crops and Soils Specialist Kansas State Univ.

  2. Essential Nutrients • Thirteen essential nutrients • Nitrogen, phosphorus, potassium, calcium, magnesium, sulfur • Iron, manganese, boron, molybdenum, copper, zinc, and chlorine • Nickel has recently been added • Micros are needed in much lower concentrations to ensure adequate supply

  3. Essential Micronutrients Minor elements or trace elements Increased interest in micronutrients Higher crop yields and micronutrient removal rates Declining soil organic matter, a major source of most micronutrients N, P and K fertilizers contain lower amounts of micronutrient impurities Excessive levels can cause toxic effects on plants In Kansas: S, Zn, Fe, and Cl. Other micronutrients: B, Mg, Cu, Mn, and Ni.

  4. Organic Matter Important source of most micronutrients. Simple organic compounds as chelates. S, Zn and B deficiencies are more likely to occur in soils low in O.M. Deficiencies of Cu and Mn are most common in peat soils.

  5. Soil pH Soil pH affects availability of micronutrients. In general the solubility and availability of micronutrients are greatest in acid soils and lowest in high pH calcareous soils. Exception is Mo. In some soils, high levels of soluble Fe, Al and Mn may be toxic to plants.

  6. Sulfur (S) Brian Lang, IA

  7. Sulfur Deficiencies • Soil Situations and Climatic Conditions Aggravating Deficiency Symptoms • Coarse textured soils (sandy soils) • Low organic matter soils • Cold, wet soils • Slow release of S from organic matter • Low atmospheric deposition • No application from • Manure • Other fertilizers

  8. Sulfur Deposition 10 kg SO4/ha = 3 lb S/acre

  9. Corn Response to Sulfur J. Sawyer, 2007

  10. Corn Response to Sulfur Application Comparison of Corn with and without Sulfur Application. Brian Lang

  11. Sulfur in the Soil Subsoil S may be significant. Profile soil test for S, 0-24 inches, also good for nitrate and Cl.

  12. Sulfur Fertilizer Recommendation Wheat S Rec. (Lb/A) = (0.6 × Y Goal) – (2.5 × % OM) – Profile Sulfur – Other Sulfur Credits Corn and Sorghum S Rec. (Lb/A) = (0.2 × Y Goal) – (2.5 × % OM) – Profile Sulfur – Other Sulfur Credits Soybean S Rec. (Lb/A) = (0.4 × Y Goal) – (2.5 × % OM) – Profile Sulfur – Other Sulfur Credits

  13. Zinc (Zn)

  14. Zinc Frequently deficient micronutrient Absorbed by plant roots as Zn++ Involved in the production of chlorophyll, protein, and several plant enzymes Deficiency symptoms Most distinctive in corn with new leaves out of whorl turning yellow to white in a band between the leaf midvein and margin

  15. Zinc Deficiencies • Sensitive crops • Corn, sorghum • Soil Situation • Low organic matter, high pH (>7.4), eroded soil • Coarse texture, restricted rooting • High P application in conjunction with borderline or low zinc availability • High soil P alone does not create deficiency • Climatic Conditions • Cool and wet soil

  16. Phosphorus and Zinc Excessive concentrations of P in the plant root result in the binding of zinc within root cells. Large amounts of starter applied P can enhance Zn deficiency if soil Zn is low and no Zn fertilizer is applied. Adriano and Murphy Kansas State University

  17. P and Zn Effects on Corn Yields St. Mary’s, KS – Kansas State University

  18. Zinc Fertilizer Recommendation Corn, Sorghum and Soybeans Zinc Recommendation Zn Rate = 11.5 – (11.25 × ppm DTPA Zn) If DTPA Zn > 1.0 ppm then Zn Rec = 0 If DTPA Zn <= 1.0 ppm then Minimum Zn Rec = 1

  19. Zinc in a Band—Corn Yield

  20. Corn Yield—Zinc Source

  21. Application Methods • Broadcast • Preferred to correct a low Zn soil test • 5 to 15 pound will increase soil test for a number of years • Inorganic Zn is more economical than chelates at these rates • Band • Very efficient method of applying Zn • 0.5 lb Zn/Acre of inorganic Zn is generally sufficient • Annual applications will be needed for low testing soils

  22. Chloride (Cl)

  23. Chloride (Cl) Wheat, corn, sorghum deficiencies in Kansas Deficiencies most likely in higher rainfall areas with no K application history - central and eastern part of state Soluble, mobile anion Addition of KCl Increased yields with high levels of available K Reduced incidence of plant disease Internal water relationships, osmotic regulation, enzyme activation and other plant processes

  24. Chloride Fertilization on Corn in Kansas

  25. Chloride Fertilization on Wheat

  26. Chloride Fertilization on Grain Sorghum in Kansas

  27. Chloride Fertilizer Recommendation

  28. Iron (Fe)

  29. Iron (Fe) Mitchell Co.

  30. Iron (Fe) Iron in the plant Catalyst in the production of chlorophyll Involved with several enzyme systems Deficiency symptoms Yellow to white leaf color Symptoms first appear on the younger leaves Wide range of susceptibility of different crops Sorghum, field beans and soybeans are more sensitive than corn and alfalfa Varieties differ within crops

  31. Factors Affecting Iron Availability High soil pH. Soils with high salt contents. Cool, wet springs. Poor soil drainage and aeration. Susceptible crops/varieties. High concentrations of nitrate-N inhibit conversion of Fe+++ to Fe++, increasing severity of iron chlorosis.

  32. Fertilizer Sources of Iron Deficiencies occur more frequently than most other micronutrients in Kansas Patchy or irregular appearance in the field Success with iron fertilization is difficult Difficulty in correcting Fe deficiency with soil-applied fertilizer Iron quickly converted to unavailable form. Certain Fe chelate carriers (EDDHA) have been effective but have not been economical and may require multiple applications Foliar Application most promising

  33. Foliar Applications Applications must be done before plants are severely damaged by chlorosis and may need to be repeated Ferrous sulfate (1-2% solution) plus a wetting agent or one of several iron chelates/complexes may be used Critical timing Soybean - by the first trifoliate leaf Sorghum - apply by the 6th leaf stage

  34. Common Iron Fertilizers Fertilizer Source Iron Sulfate Iron Chelates Other Organics Manure - best Fe (%) 19-40 5-12 5-11 ??

  35. Average animal manure micronutrient content of different animal sources

  36. Micronutrients of Little Concern

  37. ? Kent Martin kentlm@ksu.edu 620-276-8286

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