四川农区水土流失及其治理

四川省最严重的水土流失发生在东部盆地的紫色丘陵农区，泥土流失主要来自坡度≥６°的坡土。全省坡土面积３１６－６ 万ｈｍ２ ，占耕地总面积的４８ ％ ，坡土中坡度≥２５°的陡坡土占１７％ 。因此，坡土的水土流失治理是我省持续农业发展的重要基础。坡土水土流失治理，除陡坡土退耕还林种草外，还有８３％ 的坡土不仅要继续耕种，而且要持续稳定高产，治理难度大且任务艰巨。坡土水土流失治理的基本思路是以集雨拦洪（地表径流） 蓄水即治水为中心，旱、洪兼治；主要治理途径是：充分开发土壤、工程（ 以小微型蓄水工程为主） 、生物（ 森林） 三大“水库”的拦洪蓄水功能，有效集蓄和利用天然雨水资源，兴利除害，为持续农业创造良性生态系统。

Soil and Water Loss and Its Control in Agricultural Area in Sichuan Province

The purple soil hilly agricultural area in Sichuan Basin is the district where soil and water lose most seriously. Soil and water loss mainly generates in Sloping Dry Farmland with grade of slope ≥6°. Sichuan Province has 3166000hm 2 Sloping Dry Farmland and accounts for 48% of total cultivated land, in which the Steep Sloping Dry Farmland with slope grade ≥25° takes up 17% in Sloping Dry Farmland. Consequently, the control of soil and water loss on Sloping Dry Farmland is the bey to the sustainable agriculture development in Sichuan Province. As for the control of soil and water loss on Sloping Dry Farmland, the Steep Sloping Dry Farmland must be returned to the forest and the grass, the other area with slope grade <25° takes up 83%, it must continue not only to be cultivated but also kept high yield, so the control is very difficult. The control of soil and water loss on Sloping Dry Farmland must collect rains, prevent the flood (overland flow) and keep water. That is to say, water control is vital meanwhile the draught and the flood are controlled; the basic measure is both to sufficiently develop the functions of soil, engineering (mili engineering to keep water), organism (forest) which can collect rains, prevent the flood, and keep water to make good use of rains in order to set up suitable eco environment for sustainable agriculture.