稻作烟区土壤电导率和阳离子交换量的垂直分布特征与养分有效性的关系.

[ Objective ] To explore the vertical distribution of soil electrical conductivity ( EC) and cation exchange capacity ( CEC) in ricegrowing tobacco areas of Hunan province, improve the soil fertility and construct a reasonable structure of the plough layer. [ Method ] The soil EC and CEC of 0 - 50 cm profiles in Chenzhou, Hengyang and Changsha rice-growing tobacco areas were systematically compared, and the relationship between them and soil nutrients was revealed. [ Result]The results showed that the soil electrical conductivity ranged from 0. 10 to 0. 17 mS/cm,and decreased with the deepening of soil layer,and the soil cation exchange capacity ranged from 10. 55 to 14. 35 cmol/kg, which first decreased and then increased with the deepening of soil layer. The soil nutrient preserving capability of 0-30 cm soil layer was weak,30 -50 cm soil layer was medium in Changsha, 0-50 cm soil layer was medium in Hengyang. In Chenzhou, the soil nutrient preserving capability of 0 - 20 cm soil layer was medium, 20-30 cm soil layer was weak, 30 - 50 cm soil layer was strong. Electrical conductivity was positively correlated with alkali hydrolyzed nitrogen, available phosphorus, available potassium, available copper, available molybdenum, available zinc, available boron and available iron, and negatively correlated with exchangeable magnesium. The cation exchange capacity was positively correlated with available nitrogen, available potassium, exchangeable calcium, exchangea ble magnesium, available boron and available molybdenum, and negatively correlated with available manganese. [ Conculsion] The results showed that the soil salt content was suitable in rice-growing tobacco areas of Hunan province, and there was no salinization phenomenon. The soil nutrient preserving capability was moderate, and the 20 - 30 cm soil layer was the worst Therefore, it is necessary to build a reasonable tillage layer and increase the application of organic fenilizer to improve the soil water and fenilizer conservation capacity. [ABSTRACT FROM AUTHOR]