Studies On Change Law Of Inorganic Phosphorus With The Situation Of Long-Term Fertilization In Typical Soils In Our Country

With a scheme developed by Gu Yichu and Jiang Baifan for fractionalizing inorganic -P in calcareous soil, this paper studies on the change of inorganic phosphorus with time and space in the situation of long-term fertilization in six typical soil of our country. Meantime, studies on the relationship between inorganic-P and Olsen-P with Correlation Analysis,Path Analysis and Stepwise Regression Analysis. Results showed as follows:Inorganic phosphorus is mainly phosphate in the red soil,the purple soil,the fluvo-aquic soil,the loess soil and the grey desert soil. The proportion was 53.90%～72.46%,69.70%～77.36%,60.95%～77.87%,70.03%～84.94%,76.89%～86.52% respectively. The inorganic phosphorus proportion in black soil was 34.97%～48.16% and the organic phosphorus was the main part in black soil.The inorganic phosphorus of the six kind of soil except red soil is main calcium phosphate.Ca₁₀-P acounted for higher than 60% in the purple soil,the loess soil,the grey desert soil and the fluvo-aquic soil. The Ca₁₀-P only acounted for 38.3% in the black soil; The Ca-P proportion is lesser in the red soil and O-P is the mainly phosphate.The proportion sequence of each part inorganic phosphorus don't changed by fifteen years different fertilization in the grey desert soil and the fluvo-aquic soil. But it changed in the red soil,the purple soil,the loess soil and the black soil. While combine use of chemical fertilizer and organic manure, the proportion of each part inorganic phosphorus trend to equilibration.In all kinds of soils, The contents of Ca₂-P,Al-P and Fe-P in N and check treatment plots decreased gradually,especially the content of Ca₂-P. The contents change of Ca8-P,O-P and Ca₁₀-P are disaccord in the six kinds of soils. The proportions of Ca₂-P,Ca8-P,Al-P,Fe-P decreased and O-P and Ca₁₀-P increased in the treatments without P fertilization. This indicated that unused phosphorus in treatments which without P fertilization mainly shifted to O-P and Ca₁₀-P.With P fertilization, all forms of inorganic phosphorus increased more or less in the six kinds of soils. The increment in soil inorganic phosphorus caused by P fertilization mainly shifted to Ca₁₀-P in all kinds of soils except red soil. The increment mainly shifted to Ca8-P and Al-P in red soil. Under the balance fertilization and increasing organic fertilization circumstance, the applying phosphor capability of the six kinds of soils can be improved and the accumulation of the available phosphor can be increased. P fertilization could increased Ca₂-P,Al-P and Ca8-P content which had higher availability to crop, while it had little effect on the content O-P and Ca₁₀-P which had lower availability to crop.Though Ca₂-P has higher activity than other forms of inorganic phosphorus.But it's availability to crops has been confined by its proportion in the six kinds of soils(except grey desert soil). With Path Analysis and Stepwise Regression Analysis between Olsen-P and different composition of inorganic P in the six soils, it indicated that: Ca₂-P,Al-P had higher availability to crop in red soil; Al-P had higher availability to crop in fluvo-aquic soil; Ca8-P had higher availability to crop in loess soil; Ca₂-P and Fe-P had higher availability to crop in grey desert soil; Fe-P had higher availability to crop in purple soil and black soil.