Late‐season foliar fertilization with macronutrients – is there a theoretical basis for increased seed yields?

The hypothesis that leaves of soybean plants need to senesce in order to provide nitrogen for seed development has been used to explain the mechanism by which late‐season foliar applications of N P K and S solutions sometimes increase seed yields. A review of results of recent field and laboratory trials suggests that late‐season foliar fertilization does not inhibit leaf senescence and that such senescence is in any case not a primary factor in limiting seed yields.