In order to investigate the composition and transformation of clay minerals in soil nanoparticles under the combination of Chinese milk vetch and different proportions of reduced chemical fertilizer,the long-term experiment was conducted in Nanxian County,Hunan Province,where Chinese milk vetch returning(MV)was combined application with 100%,80%,60%and 40%(F100,F80,F60 and F40)ratios of fertilizer,and then the soil was divided into four particle grades(>2 000,2 000-450,450-100 and 100-25 nm),to investigate the distribution characteristics and transformation of clay minerals in different particle grades.The results showed that:1)Soil particles decreased from>2 000 nm to 100-25 nm,the relative content of illite in 2 000-450 nm and 450-100 nm particles was reduced by 8%-11%,the 1.4 nm minerals and vermiculite in 100-25 nm particles were rare or even disappeared,the contents of free iron and amorphous iron increased,and were highest in 100-25 nm particles.2)Under the combined application of Chinese milk vetch and chemical fertilizer,the transformation of minerals showed obvious difference before and after the chemical fertilizer application rate of 80%.When fertilizer was reduced from 100%to 80%,the relative content of kaolinite increased by 14.1%-51.2%,while illite decreased by 3.6%-11.7%.With fertilizer continuously reduced,kaolinite decreased by 13.7%-28.8%,but illite increased by 2.6%-18.5%.3)With the decrease of chemical fertilizer dosage,the content of free iron changed irregularly,but the content of amorphous iron increased significantly at first and then decreased,and reached a maximum of 145.31 g/kg at MV+F80 in 100-25 nm nanoparticles.In conclusion,the conversion of kaolinited,illite and amorphous iron in soil particles is significantly correlated with the reduction of fertilizer application,and the effect is most significant at the 20%reduction of fertilizer application.
Chinese milk vetchChemical fertilizer reductionNanoparticlesClay mineral
维普
万方数据
