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. Kansas State University
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.
P2O5 Zn
Yield
Leaf tissue
lb/A *
bu/A
P, %
Zn, ppm
101
0.14 12 10
102
0.16 24 80 73
0.73
162
0.41 17
Corn is highly sensitive to zinc (Zn) deficiency. High P availability can induce Zn deficiency in soils that are marginally Zn deficient. In this example from Kansas, band applying P without Zn made a Zn deficiency worse than by broadcasting the P without Zn. The corn in the background received 10 lb/A of Zn with P, and this corrected the deficiency. The soil in this example was low in both P and Zn. (Adriano and Murphy).
When plants are Zn deficient, their ability to regulate P accumulation is severely impaired. As a consequence, P absorbed by the roots accumulates in excess in the shoot (as can be seen in the data above for the Kansas example). The negative interaction between the two nutrients appears to occur in the plant, not in the soil. Zinc and phosphate can react in the soil to form zinc phosphate, but its solubility is usually sufficient to provide adequate Zn to plants. (Havlin et al., 1999).
Data source: Adriano, D.C. and L.S. Murphy Phosphorus-zinc fertilization of corn. Kansas State University, Kansas Fertilizer Handbook. pp
Havlin, J.L., J.D. Beaton, S.L. Tisdale, and W.L. Nelson Soil Fertility and Fertilizers. Sixth edition. Prentice Hall, Upper Saddle River, New Jersey
Adriano and Murphy
Kansas State University

17. P and Zn Effects on Corn Yields
P2O5 Zn
B’cast
Starter
Lb / A
Corn Yield (Bu/A)
107 10
121
115 40 93
139
140
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
Zn Rate (lb./acre)
Yield (bu./acre) 62
0.1
131
0.3
137
1.0
140
3.0
142
Used suspension with 2.5% clay
DTPA extractable Zn = 0.3 ppm

20. Corn Yield—Zinc Source
bu./acre
EDTA
136.6
Nulex-Zn
134.8
Zinc Oxide
127.5
Zinc Sulfate
138.3
Zinc rate was 0.3 lb. Zinc /acre

21. Application Methods Broadcast Band
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
Grain Yield
Chloride
Riley Co.
Brown Co.
Osage Co.
Rate
Site A
Site B
Site C
lb/a
bu/a 70 64
107
188
123 87
133 79 20 84 69
111
191
130 93 81
Soil test Cl, lb/a (0-24") 9 16 24 28 14 40 61

25. Chloride Fertilization on Wheat
Grain Yield
Chloride
Marion Co.
Saline Co
Stafford Co.
Rate
Site A
Site B
Site C
Site D
Avg.
lb/a
bu/a 45 80 51 89 83 70 73 64 69 20 47 85 54 90 75 74
Soil test Cl, lb/a (0-24") 7 14 22 15 12
*Average over either 12 or 16 varieties. Soil test Cl, lb/a (0-24")

26. Chloride Fertilization on Grain Sorghum in Kansas
Grain Yield
Chloride
Marion Co.
Brown Co.
Osage Co.
Rate
Site A
Site B
Site C
Site D
 lb/a
bu/a 87
117 63 92
102
125 88 10 94
139 71
113
106 95
126 20 97
135 72
111 96
Soil test Cl, lb/a (0-24") 9 7 43 52 29

27. Chloride Fertilizer Recommendation

28. Iron (Fe)

29. Iron (Fe)
Mitchell Co.

30. Iron (Fe) Iron in the plant Deficiency symptoms
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
Manure source
Iron
Manganese
Boron
Zinc
Copper
lb/wet ton
Dairy solid
0.5
0.06
0.01
0.03
Swine solid
19.0
1.09
0.04
0.79
0.50
Poultry
3.0
0.61
0.08
0.48
0.66
lb/1000 gal
Dairy liquid
0.9
0.11
0.12
Swine liquid
2.5
0.23
1.03
0.62

36. Micronutrients of Little Concern
Reason
Calcium
Very acid soils - Rare deficiency
Magnesium
Very acid, sandy soil
Boron
Dry, leached, low OM sands – Alfalfa or Soybeans
Manganese
High pH, High OM
Copper
High OM, Highly weathered soil
Molybdenum
Highly weathered acid soils – legumes – enough in seed?

37. ?
Kent Martin