Micronutrient Management

Dorivar Ruiz DiazSoil Fertility and Nutrient Management

OutlineOverview micronutrients

Factors to be considered

S, Zn, Cl, and Fe

Deficiency symptoms

Fertilization strategies and management

Current studies

Essential MicronutrientsMinor elements or trace elementsIncreased 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 impuritiesExcessive levels can cause toxic effects on

plantsIn Kansas: Fe, S, Zn, and Cl. Other micronutrients: B, Mg, Cu, Mn, and Ni.

Organic MatterImportant 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.

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.

Sulfur (S)

Photos by Brian Lang, IA

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

Sulfur Deficiencies

SS

NN

10 kg SO4/ha = 3 lb S/acre

Sulfur Deposition

Corn Response to Sulfur

J. Sawyer, 2007

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.

Sulfur Fertilizer Recommendation

Zinc (Zn)

ZincFrequently deficient micronutrientAbsorbed 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

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

Zinc Deficiencies

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.

P2O5 Zn Yield Leaf tissue

lb/acre bu/acre P, % Zn, ppm

0 0 101 0.14 12

0 10 102 0.16 24

80 0 73 0.73 10

80 10 162 0.41 17Adriano and Murphy, KSU

P and Zn Effects On Corn YieldsP2O5 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

Wheat response to foliar Zn and Cuwestern Kansas

• 1 lb/acre Zn• 1 lb/acre Cu• Control

B. Olson, 2009

Soil Test

Year Site Variety Copper Zinc

- - - - ppm - - - -

2007 1 Danby 1.0 1.3

2 Jagalene 1.0 1.0

3 Wesley 1.0 0.7

4 Jagalene 0.7 0.8

2008 1 Jagalene 0.6 0.2

2 Ike 1.0 1.2

3 TAM111 1.2 0.6

Wheat response to foliar Zn and Cuwestern Kansas

B. Olson, 2009

Treatment Yield2007 2008

- - - - - bu/acre - - - - Zinc 63 42Copper 65 40Control 63 42LSD (0.05) NS NS

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 = 0If DTPA Zn <= 1.0 ppm then Minimum Zn Rec = 1

Application MethodsBroadcast

– 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 ratesBand

– 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

Chloride (Cl)

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

Chloride fertilization for wheat and sorghum, in Kansas

Chloride rate Wheat yield (Var. 2145)

lb/acre bu/acre

0 66

10 71

20 71

30 73

LSD(0.05)= 3B. Gordon, 2009

Wheat response to Cl and fungicide application

Overley wheat yieldChloride rate No fungicide Fungicide

lb/acre - - - - - - - - bu/acre - - - - - - - - -0 48 54

10 57 6220 60 6430 60 64

LSD(0.05)= 3

B. Gordon, 2009

Grain Yield

Chloride Marion Co. Saline Co Stafford Co.

Rate Site A Site B Site A Site B Site C Site D Site A Site B Avg.

lb/a - - - - - - - - - - - - - - - - - - - - - bu/a - - - - - - - - - - - - - - - - - - - -0 45 80 51 89 83 70 73 64 69

20 47 85 54 89 90 75 80 70 74

Soil test Cl, lb/a (0-24")

7 7 14 22 7 14 7 15 12

*Average over either 12 or 16 varieties. Soil test Cl, lb/a (0-24")

Chloride Fertilization on Wheat

Cl Fertilizer Recommendation

Profile soil Chloride Chloride recommendation

ppm lb/acre lb Cl/acre

< 4 < 30 20

4 - 6 30 - 45 10

> 6 > 45 0Wheat, corn and sorghum

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

Iron Deficiency

Iron Deficiency - CausesIron 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.

Effect of soil nitrate?

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++

Irrigated soybean

Nitrogen application and iron chlorosis

G. Rehm, 2007

Soybean population and iron chlorosis

2.0

1.51.0Ir

on c

hlor

osis

sco

re5=

Dea

d; 1

=G

reen

Neave, 2004

Soybean population – yield

Neave, 2004Loc.1 Loc.2 Loc.2 0

10

20

30

40

50

bu/a

cre

Soybean Fe Study - 2009Varieties (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

ObjectivesEvaluate 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?

Soybean seed treatment with Fe chelate

Seed coating treatment

No seed coating

EDDHA (6%) HEDTA(4.5%) No Foliar EDDHA (6%).HEDTA(4.5%). No Foliar.

Ch

loro

ph

yll M

ete

r R

ea

din

g

35

36

37

38

39

Yes seed coating

Chlorophyll meter readings

No seed coating

EDDHA (6%) HEDTA(4.5%) No Foliar EDDHA (6%).HEDTA(4.5%). No Foliar.

Ch

loro

ph

yll M

ete

r R

ea

din

g

35

36

37

38

39

40

Tolerant Susceptible

Yes seed coating

Chlorophyll meter readings

Seed coating

No Yes

He

igh

t (i

nch

es)

0

5

10

15

20

25

30EDDHA(6%) HEDTA(4.5%) No foliar

Plant height at maturity

Seed coating

No Yes

Yie

ld (

bu/a

cre)

0

10

20

30

40

50

60EDDHA(6%) HEDTA(4.5%) No foliar

TreatmentAverage

yieldW/O Seed coating 396% Foliar 404.5% Foliar 37No 39

W/ seed coating 506% Foliar 524.5% Foliar 49No 49

Var AG3205: Low IC tolerance

Soybean grain yield

Seed coating

No Yes

Yie

ld (

bu/a

cre)

0

10

20

30

40

50

60EDDHA(6%) HEDTA(4.5%) No foliar

Soybean grain yield

Var AG2906: Very Good IC tolerance

TreatmentAverage

yieldW/O Seed coating 366% Foliar 354.5% Foliar 38No 35

W seed coating 506% Foliar 474.5% Foliar 52No 52

Are these yield values significantly different?

Effect F Value Pr > F SignificanceVariety 2.11 0.1487 NSSeed trt 69.6 <.0001 SFoliar 0.05 0.9553 NSVar*Seedtrt 0.19 0.6616 NSVar*Foliar 2.1 0.1268 NSSeedtrt*Foliar 0.1 0.9004 NSVar*Seed*Foliar 0.27 0.7631 NS

Common Iron Fertilizers

Fertilizer Source

Iron Sulfate

Iron Chelates

Other Organics

Manure - best

Fe (%)

19-40

5-12

5-11

??

Manure source

Iron Manganese Boron Zinc Copper

-----------------lb/wet ton---------------------Dairy solid 0.5 0.06 0.01 0.03 0.01Swine solid 19.0 1.09 0.04 0.79 0.50Poultry 3.0 0.61 0.08 0.48 0.66

-----------------lb/1000 gal---------------------Dairy liquid 0.9 0.11 0.03 0.11 0.12Swine liquid 2.5 0.23 0.06 1.03 0.62

Average animal manure micronutrient content

SummaryFe 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.

SummaryIncreased 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.

Questions?Dorivar Ruiz Diaz

ruizdiaz@ksu.edu785-532-6183

www.agronomy.ksu.edu/extension/