High-yield soybean (Glycine max L.) has a high rate of N uptake during grain fill which may exceed N available from biological N fixation and mineralization of soil organic N. Other research findings show a low probability of response to N applied at early grain fill for yield 60 bu/acre yield are inconsistent. The effect of applying N and S to the soil at early podfill was determined in Nebraska by conducting 56 irrigated trials, including 44 with mean yield >60 bu/acre. Mean yield increases with 27 lb/acre N applied and >60 bu/acre yield were 2.5 bu/acre in south-central, 1.6 bu/acre in northeast, and not significant in southeast Nebraska. There was no added yield with applying 54 compared with 27 lb/acre N or with the addition of 4.5 lb/acre S. Variations in soil properties and in leaf N and S concentrations were not related to yield or the response to applied N. Depending on the grain to fertilizer price ratio, application of N at early pod fill may be profitable, especially if the cost of application is low such as through fertigation.
