Changes in Soil Phosphorus Fractions and their Relationships with Selected Soil Properties After 14 Years of Combined Fertilization and Cultivation Practices in a Sloping Cropland with Entisols

Understanding the soil phosphorus (P) pool fraction subjected to fertilization and cultivation practices was conducive to improving the effectiveness of P and revealing the changes in and storage of soil organic and inorganic P. However, the changes in soil P fractions caused by long-term fertilization and cultivation remain largely elusive. This study investigated the various soil P fractions and their relationships with selected soil properties in a representative purple soil sloping cropland experiencing long-term fertilization and cultivation. The experiments comprised five treatments: no fertilizer and downslope cultivation (CK); chemical fertilizers and downslope cultivation (T1); 1.5-fold chemical fertilizers and downslope cultivation (T2); manure plus chemical fertilizers and downslope cultivation (T3); and chemical fertilizers and contour cultivation (T4). The soil P fractions were determined at 0–10 and 10–20 cm soil depths using a modified Hedley sequential method. The concentration of soil H2O-Pi and NaHCO3-Pi in T1 significantly reduced by 49.5–55.0