| Abstract: | Potassium (K) fixation by seven soils, including black soil, fluvo-aquic soil, grey desert soil, loess soil, paddy soil, red
soil and purple soil, was determined by laboratory simulation under a fifteen-year-period of long-term fertilization. Factors
affecting soil K fixation were then discussed by factor analysis and stepwise regression. Magnitude of soil K fixation rate
was as follows: the black soil > the purple soil > the loess soil > the fluvo-aquic soil > the paddy soil > the grey desert
soil > the red soil. Our results showed that soil K fixation capacity was significantly affected by the clay mineral types
in the soils. Potassium fixation capacity of soils, whose 2:1 layer silicates were dominant minerals, was affected by two
components extracted by the method of principal component analysis: the first including soil available K, slow available K
and K+ saturation, and the second including cation exchange capacity (CEC), soil organic matter (SOM) and <0.002 mm clay contents.
Potassium fixation rate was mainly affected by K+ saturation and CEC with lower added K concentration (from 0.4 to 1.6 g/L), and by K+ saturation and <0.002 mm clay content with higher added K concentration (from 2.4 to 4.0 g/L).
Supported by National Key Technology Research and Development Program of China (Grant Nos. 2006BAD02A14, 2006BAD05B09 and
2006BAD25B07), and Special Project for National Basic Research Program of China (Grant No. 2007FY220400) |
