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Micronutrient Management

Micronutrient Management. Dorivar Ruiz Diaz Soil Fertility and Nutrient Management. Outline. Overview micronutrients Factors to be considered S, Zn, Cl, and Fe Deficiency symptoms Fertilization strategies and management Current studies. Essential Micronutrients.

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Micronutrient Management

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  1. Micronutrient Management Dorivar Ruiz Diaz Soil Fertility and Nutrient Management

  2. Outline • Overview micronutrients • Factors to be considered • S, Zn, Cl, and Fe • Deficiency symptoms • Fertilization strategies and management • Current studies

  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: Fe, S, Zn, 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 and micronutrient availability • 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) Photos by 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. S N

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

  10. Corn Response to Sulfur J. Sawyer, 2007

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

  12. Zinc (Zn)

  13. 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

  14. 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

  15. Phosphorus and Zinc • Zn deficiency impairs plant P regulation. • Large amounts of starter applied P can enhance Zn deficiency if soil Zn is low and no Zn fertilizer is applied. Adriano and Murphy, KSU

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

  17. Wheat response to foliar Zn and Cuwestern Kansas • 1 lb/acre Zn • 1 lb/acre Cu • Control B. Olson, 2009

  18. Wheat response to foliar Zn and Cuwestern Kansas B. Olson, 2009

  19. 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

  20. 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

  21. Chloride (Cl)

  22. 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

  23. Chloride fertilization for wheat and sorghum, in Kansas B. Gordon, 2009

  24. Wheat response to Cl and fungicide application B. Gordon, 2009

  25. Chloride Fertilization on Wheat

  26. Cl Fertilizer Recommendation Wheat, corn and sorghum

  27. 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

  28. Iron Deficiency

  29. Iron Deficiency - Causes • Iron deficiency is caused by a combination of stresses rather than a simple deficiency of available soil Fe • Soil Chemical Factors • pH, carbonates, salinity (EC), available Fe (DTPA-Fe), high nitrate-N. • Cool, wet soils • Biotic factors • Variety, SCN, root rotting fungi, interplant competition.

  30. Effect of soil nitrate?

  31. The nitrate theory • Iron is part of the chlorophyll molecule • Iron taken up as Fe+++ (ferric) • Iron in chlorophyll exists as Fe++ (ferrous) • High concentrations of nitrate-nitrogen inhibit conversion of Fe+++ to Fe++

  32. Irrigated soybean

  33. Nitrogen application and iron chlorosis G. Rehm, 2007

  34. Soybean population and iron chlorosis Iron chlorosis score 5= Dead; 1=Green 2.0 1.5 1.0 Neave, 2004

  35. Soybean population – yield 50 40 30 bu/acre 20 10 0 Loc.1 Loc.2 Loc.2 Neave, 2004

  36. Soybean Fe Study - 2009 • Varieties (2): high and low IDC tolerance. • Seed treatment: with and without 0.6 lb/acre of EDDHA Fe (6.0%). • Foliar treatments: • 0.1 lb/acre EDDHA Fe (6.0%) • 0.1 lb/acre HEDTA Fe (4.5%) • No foliar treatment • 4 locations with 5 replications

  37. Objectives • Evaluate fertilization strategies. • Determine soil parameters (diagnostic): • Fe, Mg, P, K, Ca, OM, OC, TN, pH, EC, Carbonates, nitrate-N. • Determine “optimum” plant tissue level. • Evaluate possible interaction of parameters, both in soil and plant. • Possible Fe-Mn interaction?

  38. Soybean seed treatment with Fe chelate

  39. Seed coating treatment

  40. Chlorophyll meter readings

  41. Chlorophyll meter readings

  42. Plant height at maturity

  43. Soybean grain yield Var AG3205: Low IC tolerance

  44. Soybean grain yield Var AG2906: Very Good IC tolerance

  45. Are these yield values significantly different?

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

  47. Average animal manure micronutrient content

  48. Summary • Fe deficiency potential can not be explained well by a single soil parameter. • Development of an “ soil index” may be the best alternative. • Foliar treatment seems to increase the “greenness” effectively. But seed coating provides higher yield increases. • Select a soybean variety that is tolerant to Fe chlorosis. • Avoid excessive application of nitrogen fertilizer to the crop that precedes soybeans in the rotation.

  49. Summary • Increased interest for foliar application of nutrients. • Tissue test can provide good indication for micronutrient needs. • Increased interest for mixing micronutrients with fluid fertilizer for band application. • Seed coating with micronutrients is an alternative.

  50. Questions? Dorivar Ruiz Diaz ruizdiaz@ksu.edu 785-532-6183 www.agronomy.ksu.edu/extension/

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