Key points are not available for this paper at this time.
Abstract Yield response to foliar fertilization (N, P, K, S, solution) of soybeans Glycine max (L.) Merr. in Iowa has stimulated interest in the use of the same or similar materials in other soybean production areas. Inconsistent yield increases were obtained in Iowa, and it is unknown whether foliar fertilization is feasible where environmental conditions, type of soybeans, and other factors are different from those in Iowa. Field experiments were conducted on a Tifton sl (fine‐loamy, siliceous, thermic, Plinthic Paleudult) and on a Norfolk sl (siliceous, thermic, Typic Paleudult) in the Coastal Plain region of Georgia. Urea K‐polyphosphate mix (urea, K‐polyphosphate, and K 2 SO 4 ) and NH 4 ‐polyphosphate mix (urea, NH 4 ‐polyphosphate, KCl, and K 2 SO 4 ) treatments were foliar sprayed on soybeans during the seed filling period. All spray treatments damaged the foliage and suppressed yields with the greatest damage to foliage occurring with repeated application of foliar fertilizer. Three sprayings of a mixture containing 28, 2.9, 9.5, and 1.7 kg N, P, K, and S/ha resulted in an average (two sites) yield decrease of 10.9% for the K‐polyphosphate mix and 17.6% for the NH 4 ‐polyphosphate mix. Weight of pods, whole plants, or seeds, and seed quality were not affected by spray treatments. Absorption of applied nutrients into leaf tissue and translocation to reproductive tissue were detected only in a few instances. Increased N levels were detected only in seeds, and P levels increased only in leaves, while K levels were not changed. Under the conditions of this study, foliar N, P, K, and S fertilization of soybeans does not appear practicable for increasing yields.
Parker et al. (Tue,) studied this question.