陕西省几种黄土性土壤钾吸附固定动力学研究

A Study on the Kinetics of the Potassium Absorbing-fixating of the Loess Soils in Shaanxi

采用平衡法研究了陕西省 4种黄土性土壤钾吸附固定的动力学性质。结果表明 :1黄土性土壤不同土类钾吸附固定量、吸附固定速度及平衡时间差异很大。土娄 土粘化层和黑垆土埋藏腐殖质层的钾吸附固定量约为耕层的 2倍 ,陕南黄褐土的钾吸附固定量仅次于 土娄 土粘化层 ,黄绵土的钾吸附固定量最小 ;2供试土壤不同时段的钾吸附固定速度随时间的衰减变化符合 Vt=A+Blnt模型 ,衰减速率因土类而异 ;3供试土壤钾吸附固定过程符合 Elovich方程和一级扩散方程 ;4供试土壤钾吸附固定过程分为快、中、慢三个阶段或快、慢两个阶段 ,快反应约在 4 0 h完成 ,吸附固定钾量达总量的 64 %～ 93 % ,所用时间仅占总时间的 1 2 %～ 4 3 %。

The kinetics of the potassium absorbing fixation of the four loess soil in Shaanxi was studied by the equilibrating methods.The results indicated that:① The quantity, velocity,equilibration time of the potassium absorbing fixating are different marked in the different soils of the loess soils tested.The quantity of the potassium absorbing fixating is two times in Bt horizon(Stratified old manured loessial soil) and buried humus layer(Dark loessial soil)than that in plowed layer.The quantity of potassium absorbing fixation of the yellow cinnamon soil in the southern Shaanxi loess than the Bt horizon of the stratified old manured loessial soil.The quantity of the potassium absorbing fixating in loess soil(Yellow cultivated loessial soil) is the smallest in the soil tested.② The decreasing tendency of the velocity of potassium absorbing fixating at different time stage with the increasing of time can be described by the model of t=A+B ln t .The different soils had different decreasing rate.③ The process of the potassium absorbing fixating in soils tested can be described with the models of Elovich equation and first order diffusion equation.④ The process of the potassium absorbing fixating in the soil tested can be diveded into the three stage of fast reaction, middle reaction and slow reaction or the two stage of fast reaction and slow reaction.The fast reaction of potassium absorbing fixating was finished in 40 hours.The quantity of potassium absorbing fixating is 64%～93% of the total, the time of the fast reaction needed only 12%～43% of the total.