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Deficiencies appear as evenly pale green or yellow leaves and reduced leaf size.
Because much of the soybean plant’s nitrogen comes from fixation in the root nodules, a variety of factors that interfere with nodule formation or function may cause nitrogen deficiency symptoms. Low soil pH may result in low availability of soil molybdenum, which is required for proper functioning of nodules. Agricultural lime applications are probably the most appropriate solution, though seed treatment with molybdenum or foliar treatments of molybdenum can also be effective. Lack of appropriate Rhizobia bacteria (for symbiotic nodule formation) can result in nitrogen deficiency. This is most common in fields that have not been cropped to soybean for a long time, and may also be associated with low soil pH. Inoculation with appropriate strains of Rhizobia will solve this problem, and lime applications may also be beneficial. Sidedress applications of nitrogen fertilizer may be economical if the problem is diagnosed early enough. |