The Comparison Of Some Soil Nutrition Indices Of The Tobacco-rice Rotation Soils And Rice-rice Rotation Soils

By testing the soil samples which consisted of topsoil mixed samples and 0-20cm,20-40cm,40-75cm samples of soil profiles in order to compare the soils fertility differences with different farming ways, and they were development from the same parent material in the same topographic position from representative tobacco fields of Changning, Jianghua, Xintian and tobacco experimental station, Changsha in Hunan province. The results indicated that the tobacco-rice rotation and rice-rice rotation soils have no significant difference among the contents of organic matter, total N, total P, total K, available N, pH, CEC and soil available S, but the contents of available P (P< 0.05), available K (P< 0.01) in tobacco-rice rotation was higher than that in rice-rice rotation, and there was significant difference in soil CEC between Changning and Changsha (P< 0.05). The contents of exchangeable calcium, exchangeable magnesium, available silicon and available boron in soils were very low.The results also showed that masses of soil profile nutrients contents decreased with increasing depth, but the changes of total K and mid- and trace elements had no obvious trends. Soil middle element contents were abundant in Xintian. Soil trace elements contents were few under 20cm in rice-rice rotation soils in Jianghua. Different parent material of soils leaded to the soil profiles pH slightly acidic of Jianghua and Changsha, others were slightly alkaline.