Optimizing Phosphorus Application for Winter Wheat Production in the Coastal Saline Area

Phosphorous (P) fixation in saline soils is a concern worldwide. To investigate optimization strategies for P fertilizer application that improve P use efficiency (PUE) and crop yield in saline soil, in terms of P sources and rates, we conducted a two year field experiment in the coastal saline area of China to investigate the effects of P rates and sources, including superphosphate (SSP), monoammonium phosphate (MAP) and ammonium polyphosphate (APP) on yield, aboveground P uptake, agronomy efficiency (AE(P)), and soil available P of winter wheat (Triticum aestivum L.). Wheat yield, under the three P sources, increased with P rates and reached a plateau under 20 kg P ha(-1) SSP,18 kg P ha(-1) MAP, and 17 kg P ha(-1) MAP, respectively. The application of SSP increased the wheat yield by 9-11% compared to MAP and APP. The aboveground P uptake of winter wheat under SSP was 14% and 13% higher than MAP and APP, respectively, under the optimal P application rate. The AE(P) under SSP was higher than the other two P sources under the same P rate. SSP increased the soil Ca2+ concentration by 20-42%, but decreased the Na+ concentration by 14-18% at the P rate of 26 kg P ha(-1) in all soil layers, including 0-20, 20-40, 40-60 cm, compared to CK (0 kg P ha(-1)). The soil Olsen-P concentration under APP was higher than the other P sources. This study suggests that optimizing P sources and rates can improve wheat yield, PUE, and soil quality in the coastal saline soil.