Effects of phosphorus fertilizer on different inorganic phosphorus fractions in soils

Yellow brown soil and red soil,which were applied inorganic phosphorus(Pi) fertilizer and then cultured under the moist condition in the room for 50 days,were sampled and contents of Pi fractions were determined with Jackson-Chang's method.The results indicated that phosphorus fertilizer increased the contents of all Pi fractions in soils.On yellow brown soil the fertilized phosphorus was firstly transformed into S-P,Ca-P and Al-P,and then S-P and Ca-P converted to Al-P mainly.However,it didn't obviously influence the contents of O-P and Fe-P in this soil.For red soil the fertilized phosphorus was at first combined in S-P,Al-P and Fe-P,after that the S-P and Al-P were gradually transformed into Fe-P. Phosphorus fertilizer didn't obviously increase the contents of O-P and Ca-P in red soil.