Long-term Fertilizer Application Alters the Balance and Vertical Distribution of Phosphorus in a Calcarosol

The information on the distribution of P fertiliser in soil profile would be beneficial for better P management in farming systems. The aim of this study is to investigate how the long-term application of fertiliser P affects the vertical distribution of P in the soil and P balance. Soil samples were collected from a long-term permanent P fertiliser trial and were sequentially extracted for P fractions. There was a net negative P balance over the 66 years in the nil-P and low P (3 kg P.ha(-1)) treatments. In contrast, applying 12 kg P.ha(-1) to each wheat crop led to a highly positive P balance of 106 kg P.ha(-1) in this soil, resulting in P accumulation in the top 10 cm. Nil and low P application rates resulted in lower soil Pi content at 5 similar to 20 cm depth. The transformation of the residual P fertiliser into all Pi fractions suggests that the applied P had transferred into different P forms which are either readily available or sparingly available to subsequent crops.