Micronutrient Needs for Crops on the Southern Plains

Dave MengelProfessor of Soil FertilityKansas State University

The Essential Elements Carbon, Oxygen, Hydrogen Macronutrients

N, P, K Secondary Nutrients

Ca, Mg, S Micronutrient metals

Fe, Zn, Mn, Cu, Ni Other micronutrients

Cl, B, Mo

Micronutrient Metals

Of the five micronutrient metals: Zinc deficiency is common on corn

and grain sorghum Iron deficiency is common on corn,

grain sorghum and soybeans Manganese deficiency is not common

in the region, but is of interest due to reports of Manganese x glyphosate interactions in RR soybeans

Micronutrient Metals

Of the five micronutrient metals: Copper is not a problem in the region,

but recently “foreign experts” have been raising questions concerning potential Cu deficiencies in wheat.

Nickel is of academic interest only at this time.

Zinc

Zinc Zinc: the most common micronutrient

deficiency of corn in the region Deficiencies also are seen in sorghum,

soybeans and pecans. Deficiencies in wheat and sunflowers are

rare. A cofactor in many enzyme processes in

plants, the exact role of the zinc in these reactions is generally not known.

Zinc is generally immobile in the plant, and deficiency is commonly noted on the young tissue.

Zinc Multiple symptoms have been described

for zinc deficiency, with some genotypes responding differently. In corn a stunting, yellowing at the whorl

and intervienal striping is common. A stunting or rosetting and internode

shortening of young seedlings with distinct white band on one side of the mid-rib is also common.

Zinc Deficient Corn

Where Zinc Deficiency is Seen Zinc is low in many soils across the

region, and especially in areas of high pH, and where organic matter has been removed, such as eroded areas or land leveled fields.

Assessing Zinc Deficiency

The DTPA Soil Test is commonly used for zinc The critical level ranges from 0.5 to 1

ppm Zn for most crops Levels 0-0.5 considered strongly

deficient Applications are roughly 1 lb Zn per

0.1 ppm below the critical level

Correcting Zinc Deficiency Application of zinc can be by:

Broadcast applications of a high percentage water soluble zinc source, such as zinc sulfate, oxysulfate or zinc chelate.

Band application of these same products with starter fertilizers.

Foliar application of zinc, especially on pecans and rice.

Application of animal manure. Most manure contains large amounts of zinc

Iron Chlorosis

Iron in Plants Iron deficiency in field crops is common, especially

on corn, soybeans, and sorghum. It is less common on wheat, but does occur.

Iron is the most common micronutrient deficiency of turgrass and ornamentals in Kansas. Iron chlorosis occurs frequently on lawns in new developments or on golf greens built with unwashed river sand.

Considerable difference exists between varieties in all crops. Corn and soybean varieties are screened for iron chlorosis.

Iron is a structural component of cytochromes, hemes and other substances involved in oxidation-reduction reactions in photosynthesis and respiration.

Iron Deficiency Symptoms Iron is very immobile in plants, once

deposited in tissue, iron is not easily remobilized to younger tissue.

Deficiency symptoms are generally found in the youngest leaves on the plant.

Young leaves develop an intervienal chlorosis that rapidly progresses over the entire leaf. This may include a bleaching of the veins and in severe cases the entire leaves will turn white.

Iron Chlorosis in Sorghum

Iron Chlorosis Corn

Iron Chlorosis

Iron Chlorosis in Wheat

Where Does Fe Chlorosis Occur?

On high pH depressional soils Most commonly found in “spots” in

the field In eroded spots or leveled areas .

Assessing Iron Deficiency

The DTPA test is sometimes used, but it is not reliable

pH and OM may be better indicators

Correcting Iron Deficiency

Foliar applications of 2% ferrous sulfate May take multiple applications

Band applications of 6-10 pounds soluble iron

Animal manure Lowering pH works in home hort or turf,

but too expensive for field applications

Manganese deficiency

Manganese in the Plant Manganese is involved in photosynthesis, particularly in

the evolution of O2. It also is involved in a number of oxidation-reduction

reactions and in decarboxiliation and hydrolysis reactions. In many plant reactions Mn and Mg can partially

substitute for each other. May be a relationship with the RR gene in soybeans

causing Mn deficiency

Manganese Deficiency Symptoms

Like iron, Mn is very immobile in the plant and deficiency symptoms occur as intevienal chlorosis on young leaves.

Manganese deficient leaves tend to maintain a greenish tint, unlike iron chlorosis where they turn yellow or bronze.

Manganese deficiency is not common in the region, but occurs on high pH, high organic matter soils, found in the eastern cornbelt.

Mn and RR Soybeans Speculation that the RR gene has added

a sensitivity to Mn deficiency. Reports and research in Indiana and Kansas.

The yellow flashing which occurs after glyphosate application in some fields has been called Mn deficiency.

Research with RR isolines suggest this could be the case, but likley on marginal Mn sites.

Manganese Deficiency Corn

Manganese Deficiency Soybeans

Manganese Deficiency Wheat

Assessing Mn Deficiency

Mn Soil Tests Don’t Work pH and OM may be useful in

deficient regions (eastern US)

Correcting Mn Deficiency

Like iron, the soil contains large amounts on Mn, its an availability issue.

Foliar application Band application Band apply an acid forming

fertilizer (N)

Copper Deficiency

Where is Copper Deficiency Found?

Deficiency is not found in the Southern Plains. It looks similar to drought or heat damage on wheat and has been some confusion recently

It is common on organic soils in Canada and the Great Lakes region, and on organic soils or deep acid sands in the southeastern US, which have never received applications of copper as a fertilizer or as a fungicide.

On extremely weathered oxisols or sands in tropical regions and Australia.

Copper in Plants

Copper is involved in many complex enzyme systems where redox potential is critical. Examples include the enzymes involved in lignin and melanin production.

Copper Deficiency Symptoms Corn and wheat are the two commonly

grown field crops most likely to be deficient in copper.

Like most metals, copper is not very mobile in the plant, with deficiency symptoms occurring on the younger tissue.

Copper deficiency results in a unique necrosis and twisting of the leaf tips of young seedlings. Copper is bound very strongly by soil organic matter..

Corn

Wheat

Correcting Copper Deficiency

Broadcast applications of 5 pounds Cu, 20 pounds Copper sulfate per acre. Good residual effects.

Foliar applications of 1-2 pounds Copper sulfate per acre.

Nickel

Recently confirmed as an essential element.

Only one field deficiency ever found.

Primarily of academic interest.

Micronutrient: Non-metals Of the three non-metals:

Boron deficiency occurs rarely on alfalfa in SE KS and Oklahoma and on peanuts in OK

Old research found Mo deficiencies on soybeans in SE KS

Recent reports suggest Mo deficiency may occur on soybeans in Central Kansas also.

Chloride response occurs frequently on wheat, sorghum and corn in NE and Central KS where no potash has been applied.

Boron

Boron Deficiency Since B is involved in cell division,

deficiency symptoms are cessation of growth at the terminal bud, followed by yellowing and death of young leaves.

Severely impaired fruit and seed set are late season symptoms on many crops.

Boron deficiency is commonly confused with potato leaf hopper damage in alfalfa

Where Boron Deficiency is Seen

In Kansas, boron deficiency is occasionally seen on alfalfa, primarily in SE Kansas.

There have been reports of boron response in corn and sunflower in Nebraska, cotton in Missouri, and peanut in Oklahoma.

Boron Deficient Alfalfa

Boron Deficiency in Corn

Boron Toxicity Corn Soybeans

Assessing Boron Deficiency A hot water soluble soil test is sometimes

used for boron. However it is not well correlated with plant growth, so is not recommended.

Plant analysis is the preferred diagnostic method.

Since B deficiency is easily confused with leafhopper damage, and B toxicity can be a problem, care should be used when applying boron

Correcting Boron Deficiency Boron is highly toxic to germinating

seeds of corn and soybeans. Boron fertilizers should never be applied as a "starter fertilizer" in or near the row at planting time..

Application of boron can be by: Broadcast applications of 1-2 pounds of B

as granular borate. Foliar application of 0.1-0.5 pounds

soluble borate.

Chloride

Background Chlorine has been generally accepted as an

essential element since 1954. Responses to chloride fertilization have been

reported since the 1800’s. Chloride plays many roles in plant nutrition,

but role in disease suppression, especially leaf rust in wheat and stalk rot in sorghum and corn, sparked interest in chloride in Kansas.

Yield responses to potash on high K soils also sparked interest in other states in the plains.

Chloride Fertilization of Wheat in Kansas

Some of the first chloride work reported in Kansas was done in the early to mid 1980’s by Larry Bonczkowski comparing KCl to fungicides on leaf rust suppression.

Mark Hooker at Garden City, and Ray Lamond in Manhattan followed that up with work on yield response to chloride on wheat in the mid-80’s.

Ray Lamond also screened wheat varieties for differences in response/sensitivity to chloride.

RESPONSE OF WHEAT TO CHLORIDE FERTILIZATION IN KANSAS, 1990-2006.

_______________________________________________ Chloride applied Grain Yield Percent Chloride lbs Cl-/acre bu/A in leaf at boot _______________________________________________

0 48.4 b 0.29 c10 51.7 a 0.38 b20 52.5 a 0.43 aLSD 0.05 1.3 0.03 n 34 30

_______________________________________________

Affect of Applied Chloride on Leaf Chloride at Responsive Sites

y = -0.0004x2 + 0.0148x + 0.2443

R2 = 0.1909

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Applied Chloride, lbs/a

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Sorghum: 1996 to date Unlike wheat, no visual chloride deficiency

symptoms have been described on sorghum. There appears to be a relationship in sorghum

between chloride nutrition and stalk quality. The first chloride studies on sorghum were

conducted by Lamond in 1996. 23 chloride response trials on dryland sorghum

have been reported, by several people, primarily in central Kansas.

Response of dryland grain sorghum to applied chloride fertilizer in Kansas, 1996-2006.________________________________________________________Chloride applied Grain Yield Percent Chloride in leaf lb Cl-/acre Bu/A at boot, percent ________________________________________________________ 0 98.5 b 0.10 c 20 108.2 a 0.24 b 40 109.9 a 0.33 c LSD 0.05 2.4 0.05 n 20 11________________________________________________________

Corn: 1996 to 2001 Like sorghum, no visual chloride deficiency

symptoms have been described on corn. There appears to be a relationship in corn

between chloride nutrition and stalk quality. The first chloride studies on corn were

conducted by Lamond in 1996. Only 11 chloride response trials on dryland

corn have been reported, all in central Kansas.

Response of dryland corn to applied chloride fertilizer in Kansas, 1990-2001.____________________________________________________________ Chloride applied Grain Yield Percent Chloride lb Cl-/acre Bu/A in earleaf at tassel____________________________________________________________

0 104.4 b 0.17 c 20 108.9 a 0.27 b 40 111.6 a 0.36 c LSD 0.05 3.4 0.05 n 11 11____________________________________________________________

Soil test chloride interpretations and fertilizer recommendations for Kansas.

____________________________________________________________Soil Chloride in a 0-24" sample Cl Recommended*

Category lb/acre ppm lb/acre____________________________________________________________

Low <30 <4 20 Medium 30-45 4-6 10 High > 45 >6 0

____________________________________________________________*Recommendations for corn, sorghum and wheat only.

Molybdenum

Molybdenum in Plants

Molybdenum is involved in the nitrate reductase and nitrogenase systems in plants.

Plants require very low levels of Mo. In legumes, enough molybdenum can be present in the seed to meet the needs of the plant. But subsequent generations may need additional molybdenum.

Molybdenum Deficiency Symptoms

Molybdenum deficient plants appear stunted, light green and N deficient.

Molybdenum

Where Does Molybdenum Deficiency Occur?

On low pH, weathered soils in SE and SC Kansas. Molybdenum deficiency is not common in Kansas, but occurs most frequently on old, highly weathered acid soils.

Recent reports suggest low molybdenum in seed may be contributing to Mo deficiencies under high pH.

Assessing Molybdenum Deficiency

No reliable soil test is currently available.

Soil pH and seed molybdenum may be better indicators of molybdenum needs.

Plant analysis is a good diagnostic tool.

Correcting Molybdenum Deficiency

Liming Seed treatment with 1-2 ounces of

ammonium molybdate. Foliar applications of ammonium

molybdate of 2-4ounces per acre. Due to the toxic nature of molybdenum

to ruminant animals, molybdenum fertilization is normally not recommended.

Questions?