云南红壤坡耕地烤烟生长季土壤养分迁移特征

为实现坡耕地土壤保育和可持续利用，探究了云南红壤坡耕地烤烟生长季土壤主要养分迁移特征。结果表明：红壤坡耕地剖面土壤pH、阳离子交换量（CEC）及主要养分含量随土层深度的增加线性降低，土壤容重则线性增加，碱解氮、有效磷和速效钾含量在30 cm土层以下变幅较小；随着烤烟生育期进程，剖面土壤化学性质均有不同程度的提高。红壤坡耕地烟田垄土和冲积土主要养分含量随坡位自上而下呈降低趋势，垄土降幅小于冲积土，且相同坡位土壤团聚体结构的有机质含量以垄土较高。红壤坡耕地不同坡位烟株生长特性表现为下坡位>中坡位>上坡位。总体上，云南红壤坡耕地土壤主要养分在耕作层（30 cm）以下下移潜力较弱，坡位因素会加速上坡位土壤贫瘠化。

Soil Nutrient Migration in Flue-cured Tobacco Growing Season in Red Soil Slope Farmland in Yunnan Province

In order to realize soil conservation and sustainable utilization of sloping farmland, the main nutrient transportation characteristics of red slope soil in flue-cured tobacco growing season in Yunnan Province were explored. The results showed that soil pH, cation exchange capacity (CEC) and contents of main nutrients decreased linearly while soil bulk density increased with the increase of soil depth. The contents of alkali-hydrolyzed nitrogen, available phosphorus and available potassium varied little under soil depth of 30 cm, and with the growth period of flue-cured tobacco, soil chemical properties of profile were improved to varying degrees. The main nutrient contents of ridge and alluvial soils decreased from top to bottom of the slope, and the decrease was smaller in ridge soil than in alluvial one, the contents of organic matter in same size aggregates under same slope position condition were higher in ridge soil than in alluvial one. The tobacco plant growth characteristics in red soil slope farmland were lower slope>middle slope>upper slope. In conclusion, the downward potential is weak for major soil nutrients below the tilled layer (30 cm) in Yunnan red soil slope farmland, and the slope position factor will accelerate the impoverishment of upper slope soil.