第四纪红粘土区侵蚀土壤退化机理研究

土壤退化过程总是从环境劣化开始，进而使土壤剖面形态毁损和土质变坏，并逐步使自然肥力消失。土壤环境的劣化表现为植被衰败，从常绿阔叶林→针阔叶混交林→稀疏马尾松和草灌→裸地，与此同时，土壤剖面形态从具有完整发生层A－B－C构型，逐步形成仅有B－C构型，最后仅剩C层，土质的变坏表现为止内的板实，表层抗冲、抗蚀性能减弱。土壤物质的流失，贮水能力的下降，有效水容量降低和土壤养分元素的流失等。从中可以看到，土镶退化中最主要的是土壤贮水性能下降和养分元素的明显流失两条。因此，土壤反退化亦应从这两方面着手。

Research on Soil Deterioration Mechanism in Quaternary Red Clay Region

The initial stage of soil deterioration is from the process of soil environment worsening with destruction of soil genetic horizon and decline of soil characters and soil fertility vanishing gradually at last. The soil environment worsening shows in decline of vegetation coverage on land surface-The vegetation types change from original broad-leaved evergreen forest, coniferousbroad mixed forest, pinus massoniana-sparse shrub and herbosa to naked land finally.Meanwhile,structure pattern of soil profile with integral genetic horizons A-B-C turns gradually to B-C or only C horizon in profile structure. Worsening of soil characters exhibits compactness in soil top layer, weakening of antiuerodibility and anti-washability, loss of soil material,decreasing of water-holding capacity, lowering of available moisture content and loss of nutrient elements in soil etc.. It cap be cognized that the key points in the soil deterioration are both the decrease of soil water-holding capacity and loss of nutrient elements obviously in soil erosion process. So for soil conservation, theresistance to soil deterioration must be initiated with solving the two problems.