Relationship between phosphorus application amount and grain yield of wheat and its response to soil and climate factors

Objectives The effect of phosphorus fertilizer application on wheat grain yield and the relationship between phosphorus application amount and grain yield were analyzed in soils with different available phosphorus (P) content. The results can provide the theoretical basis for the rational application of phosphorus fertilizer and the improvement of the farmland ecological environment.

Methods In this study, a database of soil available-P, P₂O₅ application amount and wheat grain yield was established based on published papers on Chinese field experiments during the period of 1990–2017. The effect of P₂O₅ application amount (< 60, 60−90, 90−120, 120−150, > 150 kg/hm²) on wheat grain yield and the relationship between P₂O₅ application amount and wheat grain yield in soils with three soil available-P gradients (< 10, 10−20, and > 20 mg/kg) were analyzed using meta-analysis. The relationship between phosphorus application rate and grain yield of wheat, and the effects of environmental factors on the relationship between phosphorus fertilizer application and grain yield of wheat were studied.

Results The application of phosphorus fertilizer showed a positive effect on the wheat grain yield, except when applying phosphorus fertilizer more than 90 kg/hm² in soils with available-P > 20 mg/kg. In detail, in soils with available-P < 10 mg/kg, the wheat grain yield increased linearly with the increase of P₂O₅ application amount, with the strongest effect for P₂O₅ application amount more than 150 kg/hm² (36.6%). In soils with available-P of 10−20 mg/kg, P application had a positive effect on the wheat grain yield, with the strongest effect for P₂O₅ application amount of 90−120 kg/hm² (25.8%). In soils with available-P > 20 mg/kg, the relationship between wheat grain yield and P application amount was fitted well by the exponential rise to maximum equation. That is, wheat grain yield increased with the increase of P₂O₅ application amount and then reached the balance. The effect of phosphorus fertilizer application on wheat grain yield was relatively weak (< 8%) in this situation.

Conclusions The effect of phosphorus fertilizer on wheat grain yield varied with the soil available-P content and the P₂O₅ application amount. Therefore, soil available-P content should be considered when applying phosphorus fertilizer for wheat production, as proper fertilizer application not only reduce the waste of phosphorus fertilizer but also protect the farmland ecological environment.