我国北方主要土壤吸附外源钾的动力学

应用动力学的原理和自行研制的连续流动交换仪，研究了从我国北方１２ 个主要土类采集的２５ 个土壤样品对外源钾吸附过程的动力学。结果表明，开始时土壤对外源钾的吸附速率最大，随着时间的推移，吸附速率越来越低，至一定时间后吸附达到饱和。该吸附过程可以较好地用一级反应方程拟合。不同土壤的吸附动力学参数差异很大。吸附持续时间、总吸附量、最大吸附速率、平均吸附速率变幅分别为１５０ ～７２０ ｍｉｎ 、１３８.７ ～２５４９.６ ｍ ｇｋｇ-1 、６.５ ～１７.４ ｍ ｇｋｇ-1ｍｉｎ-1和０.９２ ～３.５４ ｍｇｋｇ-1ｍｉｎ-1。土壤对外源钾的吸附动力学参数与土壤粘粒含量、有机质含量及阳离子交换量之间有显著或极显著的相关性。土壤吸附钾的能力按取土地点自西向东呈明显增强的趋势。

KINETICS OF POTASSIUM ADSORPTION IN SELECTED SOILS FROM NORTHERN CHINA

The kinetics of potassium adsorption was studied, by using a self?developed continuous flow apparatus, for 25 soil samples from 12 soil types of northern China. The adsorption rate to applied potassium was highest in the beginning, and accumulative amount of potassium adsorbed increased rapidly. It became lower and lower as this process proceeded,and soil was completely saturated by potassium after a certain time. This adsorption process can be well simulated by one first order reaction. The adsorption parameters varied a lot among different soils. The period of adsorption lasted, total amount of potassium adsorbed,maximum and average rates of potassium adsorption ranged from 150 to 720min, 138.7～2549.6 mgkg-1 , 6.5～17.4 mgkg-1min-1 and 0.92～3.54 mgkg-1min-1,respectively.All these adsorption parameters are closely correlated with soil clay content,organic matter content and cation exchange capacity. There was a clear tendency that,by moving from west to east in terms of the location of the soil samples,the K adsorption power of the soils gradually increased.