Study On Different Forms Of Phosphorus And Influencing Factors Of Main Cultivated Soils In Sichuan

According to such three representative cultivated soils,paddy soil,purple soil and yellow soil in Sichuan.Considering of land use,planting patterns and fertilizing modes.Sampling soil points at the base of GPS,and each soil point applied two soil samples which were from up and low soil layers.With the help of SPSS12.0 and DPS3.01,the different forms of soil phosphorus(P) content and influencing factors were analyzed by statistical methods,such as Correlation Analysis,Variance Analysis,Path Analysis and Multiple Regression Analysis.The results shows that,(1) The content characteristics of different soil phosphorus are as follows,â‘ The variance analysis suggests that,the content of Al-P and O-P in both layers of paddy soil are significantly higher than that of purple soil and yellow soil;When the content of Ca-P in both soil layers in purple soil is significantly lower than that in paddy soil but higher than that in yellow soil.Firstly,the content order of different phosphorus in neutral paddy soil is Ca-P＞O-P＞Al-P＞Fe-P,when that in calcareous paddy soil is Ca₁₀-P＞O-P＞Ca₈-P＞Al-P＞Fe-P＞Ca₂-P.Secondly,in neutral purple soil,the Ca-P accounted for 80%of total inorganic P,O-P for 10%,Fe-P for 70,Al-P for less than 1.5%,the content order of different phosphorus in calcareous purple soil is Ca₁₀-P＞Ca₈-P＞O-P＞Al-P＞Fe-P＞Ca₂-P.Thirdly,the highest availability of soil inorganic P in yellow soil is O-P,then Fe-P,Ca-P and Al-P.â‘¡The organic phosphorus in paddy is siganificantly higher than that in purple soil.The TP and available P(AP) content of paddy soil are both significantly higher than that in purple soil and yellow soil.â‘¢The path analysis shows that,Ca₂-P and Al-P are the main AP resources in paddy soil,the multiple regression equation is y(AP)=7.112+0.638(Ca₂-P)-0.901(Fe-P)+1.126(Al-P) when Ca₂-P,Al-P and Fe-P as the independent variable,the AP as the dependent variable.In purple soil,the main AP resources are Ca₂-P and Ca₈-P,the multiple regression equation is y(AP)=2.722+0.071(Ca₂-P)-0.064(O-P)+0.047(Ca₈-P) when Ca₂-P,Ca₈-P and O-P as the independent variable,the AP as the dependent variable.However in yellow soil,the main AP resources are Al-P and Fe-P,which are independent variables to AP,the multiple regression equation is y(AP)=0.492+0.180(Fe-P)+0.365(Al-P).(2) The influencing factors are analyzed,such as soil particle composition,pH,organic matter (OM),parent materials,planting patterns and fertilizing modes,the results show that,â‘ In paddy soil,Ca₂-P,Fe-P,O-P,AP respectively have significant positive correlation with silt, furthermore,Fe-P,O-P,AP respectively have significant negative correlation with clay;In purple soil, Ca₂-P,Cas-P,AP respectively have significant positive correlation with silt,and Ca₂-P,AP both have negative correlation with clay;In yellow soil,positive correlation are observed between Al-P,Fe-P and silt,respectively,when negative correlation are observed between Ca-P,O-P and silt,respectively.â‘¡In paddy soil,Ca₁₀-P significant-positively relates to pH,and Fe-P and O-P both positively relates to pH,Al-P and AP both negatively relates to pH.In purple soil,Al-P has significantly positive correlation with pH,the total inorganic P has significantly positive correlation with pH while the total organic P has significantly negative correlation with pH;In yellow soil,Al-P,Fe-P,total inorganic P, TP respectively has negative correlation with pH.â‘¢Ca₂-P,Ca₈-P,O-P all have no significant correlation to OM,besides Ca₂-P,total inorganic P, AP,TP has positive correlation with OM respectively,and Al-P,Fe-P both have significantly positive correlation with OM in paddy soil.In purple soil,Ca₂-P,Fe-P,AP,TP positively relates to OM separately.Al-P,Fe-P,AP respectively has significantly positive correlation with OM in yellow soil.â‘£There are significant differences of soil phosphorus except O-P among the parent materials, the phosphorus contents of paddy soil which developed from Q4 alluvium are the most highest among all the paddy soils,while phosphorus contents of dry land which developed from J3P Purple Mudstone diluvium are higher than others,and phosphorus contents of yellow soil that developed from Q2F glacial are lowest.⑤Among the different planting patterns,all the phosphorus contents under wheat-rice rotation and rice-rape rotation fields are statistically higher than others,and all the phosphorus contents under corn-sweet potato intercropping are significantly lower than other planting patterns.â‘¥The contents of Al-P,Fe-P,O-P,TP and AP that under Nitrogen+ Phosphate fertilizer+ Plant ash are higher than that under Nitrogen+ Phosphate fertilizer+ Farm manure and Nitrogen+ Plant ash which has the lowest phosphorus content among all the fertilization strategies.⑦The analysis of Grey Relation Entrophy shows:OM is the most important influencing factor that influences on Al-P and organic phosphorus;while that on Fe-P,O-P,AP is pH,and on Ca-P is silt.