Effects of Chinese Milk Vetch and Reducing Fertilizer Application on Composition and Transformation of Clay Minerals in Soil Particles
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
万方数据
维普
