Is your emerging field corn lacking sulfur?


Della King

Sulfur deficiencies typically are observed in sandy soils. During emergence is the time to be monitoring your corn for deficiencies. Sulfur deficiencies will appear spotty versus uniform across a field. Sulfur uptake can be influenced by depth of roots, amount of residue cover, and drainage. In young corn, symptoms appear from the leaves of the whorl exhibiting interveinal chlorosis. Sulfur is a water soluble and mobile nutrient that is found in the upper 2-4 inches.

Typically, these deficiencies are associated with periods of frequent rainfall activity, which causes the sulfur to leach into the lower soil layers outside of the emerging corn root zone. A sulfur deficiency can be categorized as short term and long term. A soil test will indicate the sulfur index as above 50 is high, 26-50 is medium, 25 or less is low, and 10-0 is very low. In most cases, if plants are showing symptoms then you would consider taking action and the question to ask yourself is how much to apply. With mild deficiencies and you did apply sulfur sometime around planting and your soil test indicates that the sulfur index is above 25, then you should consider applying 10 pounds per acre to stimulate the plant — so it can develop a mass root base, so the roots can reach through the lower soil profile mostly likely where the sulfur is. If you have deep sandy soil with a moderate to severe deficiency, then consider applying 20 to 25 pounds of sulfur per acre. Most often, a mild deficiency corrects itself as the roots grow beyond the upper 2-4 inches of soil zone or by making an additional sulfur application — thus causing little to no yield reduction. With moderate to severe deficiencies lasting beyond the 21 days after emergence, then you could see a loss of up to 2 bushels per acre.

By taking the necessary corrective measures of applying the needed amount of sulfur per acre and with quick plant uptake and response, then the plants will have the ability to grow out of this limiting condition. Other nutrients can exhibit the same symptoms as sulfur. It is very important to have plant tissue samples submitted and problem soil samples at depths of 0-8” and 8-16” for analysis in order to determine exactly what the plants are lacking. It’s also a good idea to provide healthy plants and soil from the “good” area for comparison with the “problem” area.

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