Soil Phosphorus Fractions And Adsorption In Taihu And Chaohu Lake Basins:A Comparative Study

Phosphorus is not only the nutrient factor of crop,but also the restriction factor of algal,transformed through surface runoff migration,affecting the farmland surface source pollution and lake eutrophication.In this paper,we selected arable soil in Taihu and Chaohu Basin as the research object,and collected 25 soil samples from the surface(0-20 cm).We analyzed the basic physical and chemical properties of the arable soil,studied the distribution characteristics and influencing factors of the phosphorus in various forms,investigated the adsorption characteristics of phosphorus to reveal the potential loss of phosphorus in these basin.Here are the main conclusions:(1)The TP content of arable soils in both Taihu and Chaohu Basin was high,and the spatial heterogeneity was strong.Besides,the TP content in Taihu Basin was higher than Chaohu Basin.(2)The content of four inorganic phosphorus forms in Taihu and Chaohu Basin was the same under the Hedley Classification.The content of Ca-P was significantly higher than other forms,Fe/Al-Pi was the second,PA-Pi was the third,and the WA-P was the smallest.The PA-Po content in the Taihu Basin was similar with PA-Pi,and the Fe/Al-Po is less than 2/3 of the Fe/Al-Pi,while Chaohu Basin was opposite.The R-P was relatively low,but the spatial heterogeneity was quite strong.(3)It is found that that phosphorus release risk was great in Taihu Basin due to the lower phosphorus fixation ability.The adsorption factor intensity(K),the maximum buffer(MBC)and the equilibrium phosphorus concentration(EPC0)could be well fitted by binomial,and were positively correlated with WA-P and PA-Pi.(4)Paddy soils contained more active phosphorus,which was easier to release and spread with surface runoff.Submergienc paddy soil had the most active phosphorus and least Ca-P and R-P in TP among different types.Besides,hydromorphic paddy soil contained more R-P and had poor phosphorus fixation ability.(5)Because of the accumulation and rotation system,TP and active phosphorus content was high in the paddy field in Taihu Basin,which greatly increased the risk of phosphorus loss.In Chaohu Basin,the dry land of vegetable planting brought more nutrients by artificial fertilization.At the same time,the adsorption and buffer capacity of phosphorus in paddy field were significantly lower than that in dry land.(6)Due to the differences of TP content,soil phosphorus retention capacity and potential loss risk of Arable soils in Taihu and Chaohu Basin,different countermeasures should be taken to prevent agricultural non-point phosphorus pollution and improve the effectiveness of environmental governance.More attention should be paid to controlling the application of phosphorus fertilizer in Taihu Basin to maintain the balance of phosphorus input and output in agricultural ecosystem.On the other hand,we should focus on identifying the key sources of phosphorus export in Chaohu Basin,so as to make control and management measures more targeted.