Validation of a soil phosphorus accumulation model in the wheat-maize rotation production areas of China

A model for Olsen-P (extracted by 0.5 mol L−1 NaHCO3 at pH 8.5) accumulation in soils, established using several experimental field sites, has not been validated by a large scale dataset. In the present study, a long-term (maximally 24 years), large-scale, regional soil monitoring dataset consisting of 58 sites from four provinces (Hebei, Henan, Shandong and Shanxi) of the main wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation production areas in China was used to validate the developed model for Olsen-P accumulation in soils for both inorganic and organic P fertilization. The results showed that with fertilizer P application rates of 56.3-103 kg P ha−1, total wheat-maize yields between 12.3 and 13.1 t ha−1 were obtained with net gains of 21.7-77.9 kg P ha−1 yr−1in the soils in these areas. The accumulation of Olsen-P in the P-fertilized soils above the initial soil Olsen-P contents could be predicted by fertilizer P application rates (including organic and inorganic P sources), crop yields and soil pH. According to the model, the mean accumulation rate of Olsen-P in the main wheat-maize rotation areas of China was 1.29 mg kg−1 yr−1, which was close to the measured mean value of 1.14 mg kg−1 y−1. The soil Olsen-P accumulation model could provide a valuable predictive tool, decreasing the frequency of Olsen-P monitoring in soils and improving soil phosphorus management for both agricultural production and environmental protection.