Nitrogen Deficiency

Nitrogen is required in large amounts by the cotton plant. Most of this demand is supplied by supplemental nitrogen fertilizer applied to the soil either as a preplant, or split application. The best way to avoid deficiency problems is to follow local recommendations as to rates and amounts. However, unlike some other nutrients, nitrogen may be lost from the soil under certain conditions and requires good management.

Early and midseason nitrogen deficiency symptoms are a yellowish green leaf color, which will appear on the older leaves first, and reduced size of younger leaves. Nitrogen is mobile in the plant; therefore, the plant will transfer nitrogen from the older leaves to feed younger, developing leaves. Plant height will be reduced, fruiting branches are short, and boll shed is increased. Late season deficiency may be characterized, on plants with a moderate boll load, by foliar symptoms appearing as reddening in the middle of the canopy with few bolls retained at late fruiting sites. Nitrogen deficiency can actually delay flowering by an increase in the time to first bloom and by increasing the time interval between flowering on the same fruiting branch.

After nitrogen deficiency symptoms are detected the problem can be addressed by applying additional nitrogen as a soil application or foliar feed. Making mid and late season applications of nitrogen requires a thorough understanding of the cotton crop and the situation at hand. Before an application is made, or a sequence of applications are begun, be sure you have professional advice. Mistakes dealing with nitrogen can have serious consequences. Be sure the situation is evaluated properly and the proper course of action taken. A shortage of nitrogen can reduce yields. Excessive or improperly late-applied nitrogen can delay maturity, reduce micronaire, reduce yields and/or make the crop more attractive to insects. The best way to manage nitrogen is through a sound soil fertility program.