Characteristics of inorganic phosphorus forms in low phosphorus red soils and the role of intercropping in its regulation
To clarify the effects of intercropping and phosphorus fertilizer application on the inorganic phosphorus forms of low phosphorus red soil and to promote the efficient use of phosphorus fertilizer in acidic soil,two cropping patterns,maize monocropping(MM)and maize//soybean intercropping(MI),were used to investigate the effects of intercropping on the inorganic phosphorus forms of red soil at four levels of phosphorus application(P2O5 0,60,90,120 kg·hm-2,marked as P0,P60,P90,P120,respectively).The characteristics of inorganic phosphorus forms in the rhizosphere soil of maize//soybean intercropping was studied and the effects of intercropping on maize yield and sustainability,phosphorus uptake and phosphorus balance,and soil inorganic phosphorus forms were explored in red soil.The results showed that maize grain yield and its sustainability index(SYI),phosphorus uptake increased with the increase of phosphorus application level and reached the maximum at P90 level.The inorganic phosphorus forms of the low phosphorus red soil were dominated by O-P and Fe-P,which accounted for 71.44％-80.18％of the inorganic phosphorus pool.The content and proportion of Fe-P and Al-P in red soil were significantly increased by applying phosphorus fertilizer.Maize//soybean intercropping significantly increased maize yield,promoted phosphorus absorption and utilization,reduced soil phosphorus surplus,and significantly reduced the contents of O-P,Fe-P and Al-P in red soil.Compared with monocropping,under the P60,P90 and P120 levels,intercropping grain yield was significantly increased by 66.70％,52.44％and 74.14％,SYI was significantly increased by 55.31％,42.18％and 78.00％,and phosphorus uptake was significantly increased by 61.97％,48.67％and 74.33％,respectively,and soil phosphorus surplus was significantly decreased by 33.39％,27.27％and 17.06％,respectively.Compared with monocropping,available phosphorus content in intercropping red soil was not significantly different,while O-P and Al-P contents at P0,P60,P90,P120 levels were significantly decreased by 20.62％,16.79％,16.62％,18.48％and 21.98％,21.08％,20.19％,20.18％,respectively.The Fe-P content was significantly decreased by 19.37％,15.78％and 17.72％in P60,P90 and P120 levels,respectively.There was no signifiicant difference in Ca-P content between intercropping and monocropping red soils with low phosphorus supply(P0 and P60).At P90 and P1 20 levels,Ca-P content in intercropping red soils were decreased by 23.50％and 26.70％,respectively.Random forest model analysis showed that Fe-P and Al-P were the key inorganic phosphorus forms in intercropping red soil.The total variance interpretation of intercropping increased by 7.95％compared with monocropping.In conclusion,rational intercropping in low phosphorus red soil can increase the phosphorus uptake of maize by promoting the mobilization of insoluble inorganic phosphorus forms in red soil,which has the potential to reduce soil phosphorus fixation and improve maize yield and sustainability.
万方数据
维普
