The effect of long-term fertilizer on total P

valid P

year-and-profile P composition

the property of P absorption and desorption of the soil

the index of P requirement of the soil

and so on

were studied

with the soil treated by CK

N

NPK

NPKM

NPKS

M in the long-term fertility-assessed experiment.The results showed that: both the long-term application of chemical phosphate and chemical fertilizer plus organic fertilizer can heighten the amount of total P

valid P.In treatments applied with organic fertilizer only and chemical fertilizer plus organic fertilizer

the accumulation of Ca-P and Al-P was the main form of P composition changing in soil

chemical phosphate can increase the content of total P in soil

the increasing-range of Al-P were the most in inorganic P composition

the O-P of soil was stable relatively in all treatments.With the time extending

the increasing of higher-validity Ca-P

Al-P became the trait of P composition changing.The effect of applying on topsoil was the most

and on deep soil relatively weaker

long-term application of phosphate and organic fertilizer can prompt P moving to substratum and increase P content in the deep soil.The strength of soil absorbing external P in treatments of NPKM

M was lower obviously than that in treatments of NPK

NPKS

CK and N

organic fertilizer can advance the reusing of P-absorbed

there was 47.72% P-desorbed in P-absorbed in the treatment NPKM

42.89% in M

and less than 8% in CK

N

NPK and NPKS.The PFI of treatments MNPK and M respectively was 2.51 and 2.69

obviously less than 4.53 and 4.37 of treatments N and NP.