Distribution and movability of inorganic phosphorous on the percogenic paddy soil under continuously phosphorous fertilizer application

A three-year field experiment was conducted to study the effects of phosphorus fertilization on the distribution of different inorganic P fractions of the percogenic paddy soil in Taihu region.The results indicated: Ca-P was the dominant soil inorganic P in Taihu region,among which the content of Ca10-P was the highest.No matter P fertilizer was(applied) or not,the contents of inorganic P fractions showed same tendency in all three layers: Ca10/subP O-P and Fe-P Al-P and Ca2-P and Ca8-P.After three years P application at same site,contents of total-P,Olsen-P,inorganic P,and inorganic P fractions at surface soil layer(015 cm) were increased remarkably,but in the deeper layers(1530 and 3045 cm) no significant increase was observed.The movability of totalP,inorganic P and Olsen-P to deeper layer was descended with soil depths.The movability of Olsen-P,was the highest followed by inorganic P and total P. Plant available organic P(Ca2-P,Ca8-P,Al-P) had higher downward movability than plant no/slow available P(Ca10-P,Fe-P,O-P).The correlations between Olsen-P,and Ca2-P,Ca8-P, and Al-P at these three layers were more significant than that between O-P and Fe-P,O-P,and Ca10-P.