Micronutrient Management • Zinc Zn • Iron Fe • Boron B • Copper Cu • Manganese Mn • Molybdenum Mo • Chlorine Cl •Nickel Eight Essential Nutrients • Minor elements or trace elements • Increased interest in micronutrients – Higher crop yields and micronutrient removal rates – Declining soil organic matter, a major source of of most micronutrients – N, P and K fertilizers contain lower amounts of micronutrient impurities • Excessive levels can cause toxic effects on plants • Zn ..Cl….Fe ……. B ….Mg …………Cu, Mn, Ni Micronutrient Levels in the Soil Surface Micronutrient Lb/Acre Iron 70,000 Manganese 1,000 Boron 40 Chlorine 20 Zinc 20 Copper 10 Molybdenum 2 Organic Matter • Important source of most micronutrients • 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 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 Soil Conditions and Crops Where Micronutrient Deficiencies Most Frequently Occur Micronutrient Conditions Most Conducive Susceptible Crops Exposed subsoils, recently leveled, low organic Corn, soybeans, grain and Zinc (Zn) matter, high pH calcareous soils forage sorghums Grain and forage sorghums, Calcareous, exposed subsoils, low organic matter soybeans, field beans, Iron (Fe) soils in western half of Kansas sudangrass, Well drained soils in central and eastern Kansas with Wheat, grain sorghum, corn Chlorine (Cl) no history of potassium applications Alkaline, well leached soils in southeastern Kansas, Alfalfa, sugar beets, Boron (B) dry soil conditions soybeans, corns Molybdenum Soil pH less than 5.5, deficiencies very rare Alfalfa, legumes (Mo) Copper (Cu) Deficiencies not observed in Kansas ---- Manganese (Mn) Deficiencies not observed in Kansas ---- Nickel (Ni) Deficiencies not observed in Kansas ---- Zinc • Most 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 Zinc in the Soil • Major soil reservoir of Zn is organic matter • Zn++ ion is adsorbed by CEC sites • Factors favoring Zn deficiency – High pH, calcareous soils – Low organic matter – High phosphorus ????????????? – Sandy soils – Susceptible crops – Wet, cold soil conditions – Sugarbeet rotations P2O5 Zn Yield Leaf tissue Phosphorus lb/A * bu/A P, % Zn, ppm & Zinc 0 0 101 0.14 12 0 10 102 0.16 24 • Zn deficiency 80 0 73 0.73 10 impairs plant P 80 10 162 0.41 17 regulation. * P and Zn band-applied • 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 P and Zn Effects On Corn Yields P2O5 Zn B’cast Starter Lb / A Corn Yield (Bu/A) 0 0 107 0 10 121 115 40 0 121 93 40 10 139 140 St. Mary’s, KS – Kansas State University P and Zn Effects On Corn Yields P2O5 Zn B’cast Starter Lb / A Corn Yield (Bu/A) 0 0 131 0 20 122 109 80 0 125 119 80 20 143 175 Belvue, KS – Kansas State University Sources of Zinc • Applied at relatively low rates (0.25-15 lb Zn/A) • Zinc Sulfate – Good source for dry blends – Used to make fluid ammonia complex materials – The standard others are compared against • Zinc Oxide Much less soluble than zinc sulfate. Must be finely divided to be effective on neutral-acid soils. Do not use on high pH soils • Zinc Oxysulfate • Made by acidulating zinc oxide with sulfuric acid • Generally made from industrial waste products • Most products work fine as zinc sources, a few may have low water solubility. Minimum 50% water soluble. Prefer greater. Sources of Zn Fertilizer Zinc Source Zn (%) Inorganic 22-36 Zinc Sulfates 77-80 Zinc Oxide 20-36 Zinc Oxy-sulfate 52 Zinc Carbonate 10-20 Zinc-Ammonia Complexes Organic 9-14 Zinc Chelates 5-10-20 Other Organics Zinc Ammonia Complexes • 10-0-0-10 Zn produced by ammoniating Zinc Sulfate or Zinc Chloride and diluting in water. • Much more compatible in fluid fertilizers than zinc sulfate or oxide • The fluid source to be used. Chelates • Organic compounds that form a claw-like ring around metal ions such as Zn++ that protects the zinc from soil fixation • Chelates are more compatible than inorganic Zn sources in orthophosphate fluid solutions • Chelates are more effective than inorganic sources under certain conditions – 3 to 5 times more efficient?? on high pH soils unless banded with a polyphosphate where all Zn sources perform similarly – Rates can be cut by 3/4 to 1/2 with chelated materials?? – The residual or carryover effect of a given rate of Zn as chelate is no better than an inorganic source – Major disadvantage is the cost generally being 10 times the cost of inorganic sources Effect Of Zinc Fertilizer Water Solubility On Long- Term Zinc Soil Test Values (DTPA) Product Zn Water Application Solubility Rate Ford Dodge Colby Ness Average (%) (Lb/A) (Change in DTPA Zn Soil Test - ppm) 0 0 -0.2 0.3 0.1 0.2 0.1 15 5 0.3 1.6 0.3 0.4 0.7 15 15 0.8 1.3 1.6 1.8 1.4 50 5 0.2 1.0 0.4 0.7 0.6 50 15 1.9 2.8 2.3 2.1 2.3 96 5 1.8 1.4 0.7 1.0 1.2 96 15 2.4 3.8 2.8 3.1 3.0 Compost 5 0.0 0.7 Applied February 2003 - Sampled Spring/Summer 2004 Effect Of Zinc Fertilizer Water Solubility On DTPA Zn Soil Tests Four Location Average Change In DTPA % Water Soil Test Zinc (ppm) Zn Source Soluble Zn Rate 2004 2005 Check --- 0 0.0 0.0 Oxysulfate 15 5 0.4 0.2 Oxysulfate 15 15 1.3 1.4 Oxysulfate 50 5 0.7 0.6 Oxysulfate 50 15 2.2 2.0 Zinc Sulfate 96 5 1.1 0.8 Zinc Sulfate 96 15 3.2 2.5 Probability > f < 0.01 < 0.01 LSD (0.05) 0.8 0.6 Effect Of Zinc Fertilizer Water Solubility On DTPA Zn Soil Tests Change In DTPA % Water Soil Test Zinc (ppm) Soluble Zn Rate Thomas Ness Dodge Ford Average --- 0 0.0 0.0 0.0 0.0 0.0 15 5 0.2 0.2 0.4 0.3 0.3 15 15 1.9 1.5 1.0 1.0 1.4 50 5 0.7 0.5 0.9 0.4 0.6 50 15 2.5 2.1 2.0 1.7 2.1 96 5 0.9 0.8 0.9 1.4 1.0 96 15 3.7 2.9 2.9 2.0 2.9 Probability > f < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 LSD (0.05) 0.5 0.5 0.8 * 0.9 * 0.5 Effect Of Various Zinc Sources On DTPA Zn Soil Test 3.5 0.1984Soluble ppm DTPAZn ~Zn Change5 lbs per Zn Pound per Of 1 Water ppm Soluble DTPA Zn Zn 3.0 Insoluble0.0686 ppm DTPAZn ~Zn 15Change lbs per Zn Pound per Of 1Water ppm Insoluble DTPA Zn ZN 2.5 R2 = 0.96 2.0 Measured - 15% Water Solubility Measured - 50% Water Solubility 1.5 Measured - 96% Water Solubility 1.0 Change In DTPA Zn Soil Test (ppm) Test Soil Zn DTPA In Change 0.5 0.0 0246810121416 Total Zn Application Rate (lb Zn/A) 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 Z – 0.5 lb Zn/Acre of inorganic Zn is generally sufficient – Annual applications will be needed for low testing soils – All sources are equally effective when applied with fertilizer materials high in polyphosphates • Zn should be limited to 1 lb per 22 lbs P2O5 from 10-34-0 • If longer shelf life required, only use 1/2 lb Chloride (Cl) • Essential nutrient – 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 Chloride fertilization on corn in Kansas. Grain Yield Chloride Riley Co. Brown Co. Osage Co. Rate Site Site Site C Site A Site Site Site Site A B B C A B lb/a ------------------bu/a --------- --------- 0 70 64 107 188 123 87 133 79 20 84 69 111 191 130 93 133 81 Soil test 916242814284061 Cl, lb/a (0-24") Chloride fertilization on wheat. Grain Yield* Chloride Marion Co. Saline Co Stafford Co. Rate Site A Site B Site Site B Site C Site D Site Site B Avg. A A lb/a -----------------------bu/a --------------------- 0458051898370736469 20 47 85 54 89 90 75 80 70 74 Soil test Cl, 7 7 14 22 7 14 7 15 12 lb/a (0-24") *Average over either 12 or 16 varieties. Soil test Cl, lb/a (0-24") Chloride fertilization on grain sorghum in Kansas Grain Yield Chloride Marion Co. Brown Co.