Effect of long-term fertilization on accumulation, transformation and availability of phosphorus in Fluvo-aquic soil

Effect of long-term fertilization on accumulation, transformation and availabity of phosphorus in Fluvo-aquic soil was studied. Results showed that the contents of total phosphorus, available phosphorus, total inorganic phosphorus and various forms decreased obviously without P fertilizer; with P fertilizer the contents increased. The percentage change of Ca_2-P was the most significant, the next was Ca_8-P and Al-P. Combining NPK with organic manure could promote the availability transformation of phosphorus, Ca_2-P transformation was 34.5%, higher than 23.1% transformed with chemical P fertilizer only; Ca_(10)-P and O-P transformed were respectively 7% and 1.6%, lower obviously than 11.4% and 2.6% with chemical P fertilizer only.