晋西黄土丘陵沟壑区土壤抗侵蚀能力的试验研究

Experimental Study on Soil Anti-erodibility in the Hilly and Gully Region of Loess Plateau,Western Shanxi

通过大量的野外试验及调查,探讨了晋西黄土丘陵沟壑区土壤抗蚀性的时空变化规律、天然撂荒地的抗冲刷性能以及表土生物结皮、农耕地的犁底层等对土壤抗侵蚀能力的影响。结果表明:(1)晋西黄土丘陵沟壑区小流域的坡地土壤抗剪力及抗蚀性存在明显的时空变化规律。总体上,旱季的土壤抗蚀性高于雨季;峁顶缓坡地的土壤抗蚀性高于梁坡下部陡坡地。(2)只要土壤的整体结构不被破坏,即便水流冲刷力很大,黄土易蚀的特点也不易表现。尽量避免人为破坏黄土的整体结构,也是减少黄土侵蚀的重要手段。(3)黄土生物结皮,可大大增强土壤的抗侵蚀能力,减沙效应同结皮覆盖率成正比;犁底层在黄土地区的农耕地普遍存在,且会加剧耕作层的侵蚀作用。

Based on the field experiments and investigations, the temporal and special variations of soil anti-erodibility in the Loess Plateau region in western Shanxi were studied, and also soil anti-scouribility of fallow land and the effect of microbiologic crust on soil anti-erodibility were discussed. The results show; （1）The soil shear strength and anti-erodibility in the slopeland in this region＇s catchment presents obviously temporal and special variations. In a whole, soil anti-erodibility in droughty season is higher than that in rainy season, soil anti-erodibiliry in the gently upslope is higher than that of steep downslope. （2） While whole soil structure is not destroyed even if runoff scouribility is very great, loessial soil can＇t be eroded easily. Therefore, conserving the whole structure of loessial soil is one of the very important ways to reduce erosion. （3）Microbiologic crust improved soil anti-erodibility obviously and its effect on reducing soil loss is direct ratio to the cover percentage; plough ground floor spreading widely in loess region usually worsen erosion condition.