Management Strategies for Increasing Soybean Yield on Soils Susceptible to Iron Deficiency

Abstract

Soybean [Glycine max (L.) Merr.] production has increased by more than 55,000 ha in the last 25 yr in the western third of Kansas, a region with soils that can be prone to Fe chlorosis. The objective of this study was to evaluate the relative effectiveness of varietal selection, seed‐applied Fe fertilizer, and foliar Fe application to reduce the incidence of Fe chlorosis under irrigated soybean production. Seven locations with a history of Fe deficiency in soybeans were selected. The study consisted of a factorial design with three foliar treatments (two chelated Fe fertilizer forms and no foliar), two seed‐applied Fe fertilizer treatments (with and without chelated Fe fertilizer), and two different varieties (a nontolerant and tolerant commercial variety). Plant population, chlorophyll meter (CM) readings (V3 and V6 growth stage), plant height at maturity, and grain yield were measured. Foliar Fe application did not affect any plant parameter except for CM reading and grain yield at one location. However, the use of seed‐applied chelated Fe fertilizer significantly increased CM readings at the V3 and V6 growth stages, plant height at maturity, and grain yield across all locations. Given soil conditions conducive to the development of severe iron chlorosis, seed‐applied chelated Fe fertilizer increased yields by approximately 55% for both varieties. Chlorosis quantified as CM readings at V3 to V6 growth stage may not be correlated to the yield potential of a variety in all environments. This suggests that producers should choose the best varieties primarily based on yield potential if supplemental seed‐applied Fe fertilizer will be used.