甘肃省主要农业区土壤对磷的吸附与解吸特性

实测的等温吸附曲线与常用的Freundlich、Langmuir及Temkin的吸附模式均很吻合,全部相关系数均达极显着水平。由吸附曲线得到的土壤对磷的吸附特性值(k·x_m)差异较大,东部地区较西部高,覆盖黑垆土>黄绵土>黑麻土>灌漠土。影响土壤吸磷的因素主要是土壤有机质含量和阳离子代换量(CEC),有机质含量越高,土壤对磷的吸附结合能越小,而吸磷量增加;土壤吸附磷的解吸曲线不同层次与土壤吸附磷的结合方式不同有关。水溶性磷加入土壤后,首先形成二钙磷,其次是Al-P,再次是八钙磷,并逐渐形成更难溶的磷酸盐形式。

Phosphorus Sorption and Desorption Properties of Agricultural Soils in Gansu Province

Psorption isotherms obtained in this study were fit in very well with the Freundlich,Langmuir and Temkin equations.Phosphorus sorptivity values (k·x_m) obtained from the Langmuir equation were very much different and regularly increasing from west to east of Gansu.The order of the sorptivity values based on soil nature was dark Lu soil> Loessial soil> Heima soil> Irrigated desert soil.The main factors affecting Psorption by soil were soil organic matter content and CEC.The higher the O.M.content,the lower the bonding energy of soil,while the more HPO₄^2- was absorbed by soil.Pdesorption isotherms showed different stages of desorption,which related to the Pbonding energy by soil.After being added to soil,the soluble phosphate turned into Ca₂-P at first,then Al-P,Ca₈-P,and finally formed insoluble phosphate.