长期施钾肥水稻土对铵离子吸附特征及影响因素的研究

以长期施 K 肥的水稻土为研究对象,以不施肥处理为对照,应用Langmuir 等温吸附方程对比研究两种处理水稻土对铵离子(NH4 )的吸附特征及影响因素.结果表明:本研究中水稻土对NH4 的吸附属于受浓度梯度扩散控制的物理吸附.土壤对NH4 的吸附量随吸附溶液NH4 浓度的增大而增加,但增加的幅度随吸附溶液NH4 浓度的增加而减小.不同大小团聚体对NH4 的吸附能力存在差异.土壤对NH4 的吸附特征通过拟合Langmuir方程发现,和不施肥处理相比,长期施用K肥提高了土壤对NH4 的最大吸附量,表明K肥的施用提高了土壤对NH4 的吸附潜力,可能的原因在于长期施K肥土壤伊利石含量和pH值的增加,固定态NH4 含量的降低.

On Ammonium Adsorption Characteristics and Factors in Paddy Soil Under Long-Term Potassium Fertilizer Application

Ammonium adsorption characteristics and factors were investigated by Langmuir adsorption isotherm with long-term potassium fertilizer treatment in paddy soil. The results indicated that ammonium adsorption in the sampled soils was physical adsorption controlled by concentration gradients and the diffusion process. The quantity of ammonium adsorption in soil increased but the increasing intensity decreased with the increase of ammonium concentration in adsorption solution. Ammonium adsorption in smaller soil aggregates was higher than in bigger ones. Compared with CK treatment, long-term potassium fertilizer application improved ammonium adsorption in paddy soil, possibly resulted from the increase of illite content and pH value of soil, and the lower content of soil-fixed ammonium.