<正>通过对试验区水平梯田、杉木林和裸地三种不同处理地段水土流失状况的定位观测，以及地表迳流水水质和土壤理化性状的分析，认为水平梯田和茂密的林木覆被地表，不仅大大减低土壤侵蚀量，而且能降低土壤营养物质的流失量。据研究，水平梯田和杉木林区的年土壤侵蚀模数分别力荒坡对照区的２．４％和４．０１％，年地表迳流系数分别为对照区的４２．３％和３２．３％；梯田区氮、磷、钾和有机物质的流失量分别比对照区低６７．２６％，７０．４９％，６６．４％和９５．５７％；杉木林区分别比对照区低７２．０７％，７７．０２％，４３．１８％和９０．７％；此外，水平梯田和杉木林地对滞洪和减洪、增加土壤入渗方面也有重要作用，其产流时同比对照区迟３０－５０ｍｉｎ，洪峰流量减低２－３倍。

On the basis of orientutive observation made of the soil and water loss on 3 plots(terracedfield, Chinese fir plantation and bare spot), and the analysis of surface runoff water quality and soilcharacteristics, it is believed that building terraced field and planting trees on the sloping tillage fieldscan decrease not only the quantity of water and soil loss, but also the loss of nutrient matter from soil.The modulus of soil erosion on the horizontal terraced field and Chinese fir plantation are 2. 4% and4. 01% of bare plot. The index of surface run off on the former two sites will decrease by 57. 7% and67. 7% than that on the bsre plot. The loss of N. P. K and organic matter on the horizontal terracedfield is 67. 26%, 70. 4 %, 66. 4 % and 95. 57% lower than that on the bsre plot. and also the loss ofN. P. K and organic matter on Chinese fir plantation is 72. 07 %, 77. 02%, 43. 18% and 90. 7%lower than that on the bsre plot. Moreover, the time of surf see runoff on the horizontal terraced fieldand Chinese fir plantation is held up by 30 min as compared with bare plot. and the flowing quantityon the floodpeak will decrease 2 to 3 times.