不同土壤对钾的选择吸附特性

用K Ca交换平衡法对砖红壤、红壤、土、黑土和水稻土K的选择吸附特性研究结果表明 :KG 和KV 系数随着K Ca平衡体系中吸附相中钾与钙比率的变化而改变 ,其曲线特征说明土壤胶体存在着对K亲和力不同的吸附点位。在低钾饱和度时 ,土壤对K的高选择吸附主要归于粘粒矿物楔形区域电荷点位吸附 ,五种土壤楔形区域相对吸附点位顺序为 :黑土 >土 >水稻土 >红壤 >砖红壤 ,该相对吸附点位顺序与土壤含有风化云母和蛭石有关。在高钾饱和度时 ,五种土壤对K的吸附主要发生于粘粒矿物的晶层表面电荷点位 ,粘粒矿物的晶层表面电荷起源也许起决定作用 ,此时KG 选择系数的大小顺序为 :砖红壤 >红壤 >黑土 >土 >水稻土

SELECTIVITY OF POTASSIUM ADSORPTION BY SOILS

Selectivity of K adsorption was studied using an approach of K Ca exchange equi librium on soils with a range of chemical and physical properties, including Lat osol, Red soil, Lou soil, Black soil, and Paddy soil. The results indicated that the values of K G and K V varied with the ratios of K to Ca in adsorb ed phase. The phases of curves suggested that sites differing in affinity for K existed on soil colloids. At low K saturation, the high selectivity for K can be attributed to wedge sites existing in the clay minerals. The number of wedge si tes increased in the order of Black soil > Lou soil > Paddy soil > Red soil > Latosol. The number of sites was related to the occurrence of weathered mica and vermiculite. At high K saturation, the K G increased in the order of Latoso l > Red soil > Black soil > Lou soil > Paddy soil, which was greatly influen ced by the origin of charges on colloids.;