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Sponsored: Sulfur Deficiencies in Corn

The greater your crop yield, the more likely you may experience a sulfur deficiency in following crop years.

Sulfur, the often-forgotten nutrient, is considered a secondary nutrient, but is equally important to crop yield as the primary nutrients nitrogen, phosphorus and potassium.

The previously held belief that sulfur deficiency was limited to sandy soils has since been proven inaccurate. While sandy soils and those fields with low organic matter are more susceptible to sulfur deficiencies, sulfate also may be lost by leaching and through the atmosphere via volatilization. Cool, wet soils at planting time, no-till planting systems and poorly drained fields all can contribute to a loss of plant-available sulfur.

Symptoms of sulfur deficiencies include stunted plants, leaves that are a light green color, or are experiencing leaf striping or yellowing while the leaves’ veins remain green.

According to the University of Minnesota Extension Service, sulfur deficiencies will be first visible in a plant’s newest leaves, and are often misdiagnosed as an iron deficiency. To properly diagnose a sulfur deficiency, plant material should be collected for a nutrient analysis of the plant tissue.

Often, symptoms of sulfur deficiency wane as temperatures rise and organic matter that is present in the field begins to decompose. Fertilizer is generally recommended only if the identifying leaf striping does not vanish by the fifth leaf stage of corn.

Because more than 90 percent of plant-available sulfur is in the form of soil organic matter, soil tests for sulfur may not be accurate.

Although generally not the most accurate way to determine sulfur availability, soil sampling is the most proactive way to determine how to best manage a field’s overall nutrients. After harvest, sample the top 6 inches of soil and send to a professional soil laboratory for a complete analysis. Collect samples, at minimum, every three years.

Match fertilizer treatments to yield expectations, hybrid performance, soil type, pH level, available organic matter and crop history.

Corn hybrid selection and fertility planning are key in alkaline, or high-pH, soils. High-pH soils reduce the availability of plant nutrients.

In cases of high-pH soils, plant growth often requires greater levels of zinc, sulfur, iron and phosphorus. Follow the soil test lab’s recommendation for your yield goal and gather input from your agronomist. For a healthy crop, combine zinc, iron, sulfur and some phosphorus in a starter fertilizer blend during planting. The sulfur will amend the soil and lower the pH in the root zone, making zinc, iron and phosphorus more available to the corn plant.

For more information, contact your local Mycogen Seeds commercial agronomist or visit Mycogen.com/agronomy.

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