紫色土K+吸附解吸动力学研究

从国家紫色土肥力与肥料效益监测基地定位试验上 ,在第 10年水稻收获后从 0～ 30cm土层采取土壤样品 ,研究土壤K 吸附、解吸动力学过程。结果表明 ,不同施肥处理土壤K 吸附、解吸反应分别在2 4～ 32min和 4 6～ 6 4min达到平衡 ,吸附、解吸平衡量分别为 14 1～ 19 2cmolkg-1和 11 6～ 17 5cmolkg-1。相关分析说明 ,土壤阳离子交换量 (CEC)及粘粒含量是影响吸附平衡时间、吸附平衡量的重要因素 ;CEC、交换钾量是影响解吸平衡时间、解吸平衡量的重要因素。由此可见 ,长期不同施肥对土壤CEC、粘粒及交换钾量产生影响 ,从而影响了紫色土K 吸附、解吸平衡时间及吸附、解吸平衡量。平衡前钾离子的吸附、解吸速度及吸附、解吸率与反应时间lnt间存在良好的线性关系。其中反应速度直线和解吸率直线的斜率、初始反应速度及初始吸附率均与CEC、粘粒含量密切相关。Elovich方程和一级扩散方程分别为描述紫色土K 吸附、解吸反应的最优与最差模型 ,指数方程和抛物线扩散方程拟合性介于Elovich方程和一级扩散方程之间。由此可见 ,紫色土K 吸附、解吸过程不是一个单纯的过程 ,而是一个包括土体膨胀、吸附位活化、表面扩散等诸多因素的复杂过程。

STUDY ON K+ ADSORPTION-DESORPTION KINETICS OF PURPLE SOIL

Soil samples were taken from 0~30 cm layer from selected plots with various fertilization treatments from a 10 years fixed site field trial in the National Purple Soil Fertility and Fertilizer Efficiency Monitored Base.Kinetics of K adsorption and native K desorption of the soil samples were studied.Results showed that K⁺ adsorption and desorption equilibrated in 24~32 min and 46~64 min, respectively, and the capacity of K⁺ equilibrium adsorption and desorption were 14.1~19.2 cmol kg^-1 and 11.6~17.5 cmol kg^-1, respectively.Correlation analysis indicated that soil cation exchange capacity (CEC) and clay content were important factors that affected the time and the capacity of K⁺ equilibrium adsorption; soil CEC and exchangeable K content were important factors that affected the time and capacity of K⁺ equilibrium desorption.As mentioned above the effects of long-term different fertilizer application on soil CEC, clay content and exchangeable K content affected the time and capacity of K⁺ equilibrium adsorption and desorption in purple soil.