不同生态条件下长期施钾对土壤钾素固定影响的机理

采用X射线衍射分析技术和室内模拟法，研究了长期施钾对不同生态条件和不同轮作制度下黑土、塿土和灰漠土钾素固定的影响机理.结果表明，长期施钾对水云母含量较低土壤的钾素固定能力影响较大.与不施钾土壤相比，水云母含量较低的黑土和含量较丰富的塿土在外源钾加入浓度在400～4000 mg·kg^-1范围内，对外源钾的固定量分别降低了75～747mg·kg^-1和16～238 mg·kg^-1，而水云母含量丰富的灰漠土的固钾能力无明显变化.长期施钾主要通过影响土壤含钾矿物组成对土壤固钾能力产生影响，即延缓或阻止水云母向云母-蒙脱石混层层间矿物的转化，使土壤对外源钾的固定能力降低；另外，长期施钾使土壤缓效钾含量和K⁺饱和度增加，土壤固钾能力降低.

Effects of long-term potassium fertilization on potassium fixation in soils under different ecological conditions: A mechanism study.

By using X-ray diffraction and laboratory simulation, this paper studied the effects of long-term potassium (K) fertilization on K fixation in black soil, loess soil, and grey desert soil under different ecological conditions and cropping systems. The results showed that long-term K fertilization had greater effects on the K fixation capacity of soils with lower hydromica content. When the K application rate was 400 to 4 000 mg x kg(-1), the K fixation capacity of black soil and loess soil, whose hydromica contents were low or relatively low, decreased by 75-747 mg x kg(-1) and 16-238 mg x kg(-1), respectively, compared with no K application, while no change was observed in grey desert soil whose hydromica content was high. Long-term K application could affect the changes of soil K-bearing minerals, i.e., slowing down or holding back the transformation of hydromica into mixed-layered mica-smectite, and consequently, decreased the K fixation capacity of soil. The increase of soil slow-available K content and K+ saturation owing to the long-term K application also induced the decrease of the K fixation capacity.