【摘要】 【目的】探索不同轮作方式和不同气候下,长期施钾对土壤钾素固定的影响。【方法】采用室内模拟法和X射线衍射分析技术研究了中国3种典型农田土壤,即灰漠土、潮土和紫色土在长期施钾条件下对外源钾固定能力的变化,并分析了影响土壤钾素固定的主要因素。【结果】在外源钾加入浓度0.4～4.0g·L-1的范围内,长期施钾与不施钾相比,水云母含量较低的紫色土对外源钾的固定量和固定率显著降低,分别降低了91～559mg·kg-1和14%～23%;水云母含量较丰富的潮土固钾量和固钾率略有降低,分别降低了35～274mg·kg-1和6%～8%;而水云母含量丰富的灰漠土固钾能力没有发生明显变化。长期施钾对3种土壤SOC、CEC和<0.002mm粘粒含量均无显著影响,而缓效钾和K+饱和度分别增加了11.3～349.9mg·kg-1和11%～65%。【结论】长期施钾主要是通过影响土壤含钾矿物组成的变化,即水云母向云母-蒙脱石混层层间矿物的转化,而影响土壤钾素的固定,长期施钾延缓或阻止了这种转化,使土壤对外源钾的固定能力降低;土壤缓效钾含量和K+饱和度增加,也使土壤固钾能力降低。更多还原

【Abstract】 【Objective】The effect of long-term potassium(K) fertilization on soil K fixation was studied under different cropping systems and climates.【Method】Samples taken from NP and NPK treatments in three typical soils(grey desert soil,fluvo-aquic soil and purple soil) were analyzed for revealing K fixation changes and the factors affecting K fixation using laboratory simulating methods and X-ray diffraction.【Result】The results showed that when added,K ranging from 0.4 to 4.0 g·L-1,the K fixation capacity and K fixation rate of purple soil with a low hydromica content decreased significantly in NPK treatment. The decline value ranging from 91 to 559 mg·kg-1 and 14% to 23%,while fluvo-aquic soil with an abundant hydromica content decreased slightly,and the decline value ranging from 35 to 274 mg·kg-1 was 6% to 8%. However,grey desert soil with very high hydromica content,remained constant,compared to the NP treatment. The contents of SOC,CEC and <0.002 mm clay in the three soils remained unchanged under long-term K fertilization. In contrast,the slow available K content and K+ saturation were increased,rangingfrom 11.3 to 349.9 mg·kg-1 and 11% to 65%,respectively.【Conclusion】 Long-term K fertilization arrested the transformation of hydromica into mixed-layered mica-smectite component,making K fixation capacity decrease.The increase of the slow available K content and K+ saturation induced the decrease of the K fixation capacity.更多还原