恒电荷土壤与可变电荷土壤K^+的吸附特性  

Study on Characteristics of K^+ Adsorption by Constant Charge Soils and Variable Charge Soils

作　　者：徐明岗[1] 

机构地区：[1]中国农业科学院土壤肥料研究所,北京100081

出　　处：《土壤肥料》2002年第2期13-17,共5页Soils and Fertilizers

基　　金：国家自然科学基金 (498310 0 5 );中国博士后科学基金资助项目

摘　　要：对我国 3种典型可变电荷土壤和 4种恒电荷土壤在不同 K+浓度和 p H下 K+的吸附特性进行了研究。结果表明 ,两类土壤 K+ 吸附量均随平衡 K+ 浓度增加而增加 ,在低浓度 (添加K+ 0 .1～ 1.0 mmol/ L )时两者符合线性 ,在高浓度 (添加 K+ 0 .5～ 5 .0 mmol/ L )下两者符合Langmuir方程。L angmuir方程的参数 K两类土壤间差异不大 ,但以可变电荷土壤 >恒电荷土壤 ,说明前类土壤 K吸附结合能较大 ,吸附 K+不易解吸 ,K+有效性较低。p H降低使土壤 K+吸附量减少 ,但恒电荷土壤与可变电荷土壤减少的机理不同 ,前者主要是由于 H+ 与 K+ 的竟争吸附 ,而后者主要是由于表面负电荷减少而引起的电性引力的改变。The adsorption of potassium ions by four constant charge soils and three variable charge soils of China were measured under different pH and various concentrations of potassium as KCl. The results showed that although the amount of potassium adsorbed by soils increased with increasing concentration of potassium ions, the linear relationship was only found in lower potassium concentration range from 0.1 to 1.0 mmol/L. At higher potassium concentration within the range 0.5 to 5.0 mmol/L, the adsorption can be described by the Langmuir equation satisfactorily. The adsorption energy parameter (K) calculated from the Langmuir equation was greater in variable charge soil than that in constant charge soil. Which indicated that desorption of potassium from constant charge soil was easier and the availability of potassium in constant charge soil was higher than that in variable charge soil. Although the adsorption of potassium decreased with decreasing pH in two group soils, the decreasing mechanisms were different. Competitive adsorption between potassium and hydrogen ions was major reason in constant charge soils, while the electric force changed largely in variable charge soils.

关 键 词：恒电荷土壤 可变电荷土壤 K^+ 吸附特性 土壤钾 

分 类 号：S153[农业科学—土壤学]