Potassium fixation and affecting factors of three typical soils under long-term potassium fertilization in China

Китайский. 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。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。在外源钾加入浓度0.4～4.0 gand#8226;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91～559 mgand#8226;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35～274 mgand#8226;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0.002 mm粘粒含量均无显著影响，而缓效钾和K+饱和度分别增加了11.3～349.9 mgand#8226;kg-1和11％～65％。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。

Английский. The effect of long-term potassium (K) fertilization on soil K fixation was studied under different cropping systems and climates. 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. The results showed that when added, K ranging from 0.4 to 4.0 gand#8226;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 mgand#8226;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 mgand#8226;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, ranging from 11.3 to 349.9 mgand#8226;kg-1 and 11% to 65%, respectively. 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.