ABSTRACT
In this study, we examined the effects of four phosphorus treatments on crop yields, and analyzed crop phosphorus uptake and phosphorus utilization efficiency, as well as changes in soil phosphorus deficit in maize-wheat rotation system, based on a 7-year field experiment in Baoding City, Hebei Province. The results showed that long-term phosphorus application significantly increased the yield and phosphorus uptake of maize and wheat. The yield and phosphorus uptake of maize and wheat showed a parabolic trend that first increased and then decreased with the increases of phosphorus application. The utilization efficiency of phosphorus fertilizer in the corn season was higher than that in the wheat season under various phosphorus application treatments. The cumulative utilization efficiency of phosphorus fertilizer in the wheat season showed a downward trend. The decline rate showed that optimized phosphorus application > 70% optimized phosphorus application >130% optimized phosphorus application. The cumulative utilization efficiency of phosphorus fertili-zer in the corn season showed an upward trend. For the rising rate, the optimized phosphorus application > 70% optimized phosphorus application > 130% optimized phosphorus application. Both the apparent phosphorus surplus and the accumulated phosphorus surplus of the soil without phosphorus application were under phosphorus deficiency. Under the treatment of phosphorus application, soil phosphorus showed a status of phosphorus surplus. The higher the phosphorus application rate, the longer the accumulation period, the higher the soil phosphorus surplus. Under the straw returning condition, phosphorus application rate for wheat of 105-150 kg·hm-2 and the phosphorus application rate for maize of 63-90 kg·hm-2 in Hebei fluvo-aquic soil could ensure the high crop yield, keep the phosphorus utilization efficiency at a high level, and reduce soil phosphorus accumulation and environmental risks.