Agronomy Talk

Agronomy Talk: SULFUR DEFICIENCIES IN CORN

Published on Monday, April 29, 2019

CLICK HERE FOR A DOWNLOADABLE VERSION OF THIS AGRONOMY TALK UPDATE

In the past, plant nutrition management was largely focused on nitrogen, phosphorus, potassium, and calcium, since these nutrients are needed in the greatest quantity. Reports and field observations of early-season “striped corn” have become more common across the Midwest over the past decade (Figure 1 and Figure 2).

From a distance, corn plants may appear yellow or pale green, possibly suggesting a nitrogen deficiency. Upon closer inspection, the leaves of young plants (typically between the V3 and V7 growth stage) will display interveinal yellowing, while the area near the leaf veins remain green. Since symptoms appear on newer developing leaves, this indicates a deficiency of a nutrient that is immobile in the plant. Sulfur and manganese are both immobile nutrients in plants that can show similar deficiency symptoms in corn.

Some agronomists suggest that if the striping extends to the leaf tip, the deficiency is most likely manganese. However, if the striping does not extend to the leaf tip, it is sulfur deficiency.

In season, the most reliable method to determine a nutrient deficiency in a growing crop is through tissue testing. The acceptable concentration of sulfur in corn prior to tasseling (VT) is between 0.15 to 0.50%. The acceptable concentration of manganese in corn prior to VT is between 15 to 300 ppm. For additional information on tissue testing methods and nutrient sufficiency levels, please visit A&L Great Lakes Laboratories at algreatlakes.com.

Over time, many soils in the Midwest have become sulfur-deficient for various reasons. One of the largest contributing factors to this is lower atmospheric sulfate deposition due to the Clean Air Act Amendment in 1990. Figure 3 indicates the 25-year change in atmospheric sulfate deposition. Most of the Midwest now receives only about 3 lb./A. of sulfate sulfur per year.

Sulfur is a mobile nutrient in the soil, therefore soil test results can provide some guidance but are not definitive for determining plant-available S. An acceptable level of sulfur from a soil test is between 13 to 30 ppm (26 to 60 lb./A.). This optimum soil test level for sulfur will depend largely on the organic matter (OM) content, soil texture, drainage, and yield goals.

Choosing a Sulfur Product

  • Remember, sulfate sulfur is mobile in the soil and easily leachable, so time your applications appropriately.
  • Dry, pelletized elemental sulfur can take anywhere from 6 to 9 months to break down and be available for crop uptake.

Since the amount of sulfur supplied by soil OM is dependent on mineralization with heat and moisture throughout the growing season, the amount of sulfate sulfur supplied by the soil can vary each year. In general, 3 to 5 lb./A. of sulfur can be mineralized for every 1% of soil OM. Therefore, given a soil with 3% OM, 9 to 15 lb./A. of sulfur may become available during the growing season for crop uptake.

Given the information above, along with total crop needs illustrated in Table 1, it should be easy to understand why we are seeing more cornfields with “striping” early in the growing season. There are many different options for incorporating sulfur into your fertility plan. Some of these common methods are listed in Table 2. If the need for sulfur is identified in your fields, it is highly recommended that you contact your local Beck’s representative for further information on how to best address these needs in your fertility program.

CLICK HERE FOR A DOWNLOADABLE VERSION OF THIS AGRONOMY TALK UPDATE

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Chad Kalaher
Chad Kalaher>

Chad Kalaher

Beck’s Hybrids team sales agronomist for 22 counties in NE ¼ of IL and 7 counties in NW IN. Raised on grain and livestock farm in southern IL. B.S. Agronomy 1995 – University of Illinois, M.S. Weed Science 1997 – North Carolina State University. Previous positions in seed industry as researc

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Beck’s Hybrids team sales agronomist for 22 counties in NE ¼ of IL and 7 counties in NW IN. Raised on grain and livestock farm in southern IL. B.S. Agronomy 1995 – University of Illinois, M.S. Weed Science 1997 – North Carolina State University. Previous positions in seed industry as research agronomist, district, and regional sales manager.

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