Phosphorus fertilizer optimization is affected by soybean varieties and placement strategy

Abstract

Soybean (Glycine max (L.) Merr.) response to phosphorus (P) fertilization can vary by fertilization strategy, tillage system, and soybean variety. The objectives of this study were to access possible differences in soybean productivity and P fertilizer efficiency as affected by contrasting soybean varieties and P fertilizer placement. The effects of two soybean varieties and six P fertilizer placements on soybean shoot dry weight, P uptake, apparent P recovery, seed P concentration, seed yield, P removal, and partial P balance were investigated in four sites in Kansas, during the 2014 and 2015 growing seasons. Band fertilizer applications increased the apparent P recovery at the soybean V3 growth stage and increased the shoot dry weight up to 9.13 and 12.9% compared to broadcast and control, respectively. Likewise, the band fertilizer treatments increased the P uptake by 30% compared to the control plots. On the other hand, the P concentration in soybean tissue at the R3 growth stage was higher under broadcast treatments. Yield differences were observed between variety selection only and varied by site. The good soil drainage variety increased the P removal by the seed on 5 and 6.9% at Ottawa 2015 and Scandia 2014, respectively, compared to the poor soil drainage variety. In general, band-applied treatments resulted in P fertilizer optimization during early soybean growth whereas broadcast treatments optimized fertilization efficiency during the soybean reproductive stage. The lack of soybean yield response to P fertilization suggests that P was not the limiting factor for yield response in this study.