Predictive Model for Phosphorus Accumulation in Paddy Soils with Long-Term Inorganic Fertilization

Prediction of accumulation of available phosphorus (P) in paddy soils is crucial for the best management of P fertilizers. Based on the long-term double-rice rotation systems, a predictive model for accumulation rates of Olsen P in paddy soils with chemical fertilization was developed. In paddy soils with more than 40 kg applied P ha−1, the accumulation of Olsen P in the soils could occur. With the target rice yield of 10 tons ha−1 per year, the increases in Olsen P in paddy soils were estimated by the model as 0.7, 2.2, and 3.8 mg kg−1 when P application rates are 40, 60, and 80 kg P ha−1, respectively. The accumulation rate of Olsen P was relatively high in paddy soils. The predictive model can be used to predict accurately the concentrations of Olsen P in paddy soils based on initial Olsen P, P application rate, and crop yield and to optimize P fertilization for rice crop production and environmental protection.