Effects Of Long-term Fertilization On Soil Inorganic Phosphorus Fractions And It's Profile Distribution

By the Jiang-Gu inorganic phosphorus fractionation method,this paper studied the forms and compositions of inorganic on irrigated desert soil in the oasis area of Zhangye after 25 years located experiment. In order to compare the effects of long-term different fertilization on inorganic phosphorus fractions, content and soil profile distribution. It is helpful to improve the utilizing efficiency of P on irrigated desert soil in the oasis area of Zhangye.This study set-up eight treatments: no fertilizer treatment(CK), nitrogen fertilizer(N), nitrogen and phosphate fertilizer(NP), nitrogen and phosphate and potassium fertilizer(NPK), organic and nitrogen fertilizer (MN), organic fertilizer and nitrogen and phosphate fertilizer(MNP), organic with nitrogen and phosphate and potassium fertilizer(MNPK). The rotation sequence was wheat followed by field pea. Results showed as follows:1.Of the total Inorganic P(Pi), Ca phosphates(Ca-P) were the dominant Pi fractions meanwhile accounted for 71.0% in 0²0cm soil layer and 70.5% in 0⁴0cm on average. Pi fractions varied in the order of Ca₁₀-P > O-P >Fe-P> Ca₈-P >Ca₂-P> Al-P.2.Long-term application of different fertilizers, except N treatment, can increase the content of different inorganic phosphorus fractions. The increasing content of inorganic phosphorus fractions among treatments varied in the order of: Ca2-P, MNP>MNPK>M>MN>NPK>NP>CK>N; Ca₈-P, NPK>MNP>MNPK>MN>NP>M >C >N; Ca₁₀-P, MNP>NP>MN>MNPK>NPK>N>M>CK; Al-P, MNP>MNPK>M >MN>NP>NPK>CK>N; Fe-P, MNP>MNPK>NP>MN>M>NPK>N>CK; O-P: NP> MNP > MNPK>NPK>M>MN >N>CK。3.Of the Pi, Ca₂-P, Ca₈-P, Al-P, Fe-P tended to decline with the soil depth among the eight treatments. Ca10-P accumulated in the 5¹0cm depth of the tested soil. O-P didn't show clear changes in the soil depth despite some fluctuation. 4.The IPi of inorganic phosphorus fractions with different fertilizers under 0⁴0cm soil layer compared to the IPi of inorganic phosphorus fractions with no-fertilizers,shows that: except that the IPi of Ca₂-P, Ca₈-P with N treatment reduced and the IPi of Ca10-P with N treatment increased, other treatments can increase the IPi of Ca₂-P, Ca₈-P, Fe-P , Al-P and reduced the IPi of Ca₁₀-P.5.Long-term application of fertilizers can improve soil phosphorus in cultivated layer(0²0cm), especially, the application of animal manure and chemical fertilizers in combination significantly increase the soil inorganic P content. Extent of increasing content of inorganic P, animal manure and chemical fertilizers in combination is higher than that of chemical fertilizer treatment or animal manure.