关键词: 三峡, 农业人口

Abstract: In the projected reservoir of the Three Gorges on the Yangtse River,there are 440000 inhabitants living on tarming.For the resettlement of them, one possibility is the expansion of agriculture in 13 counties and cities in the immediate neighbourhood.This is a mountainous terrain dseply dissected by streams. More than 18% of the load is cultivated, and a 17.6% of the ultivation is distributed on steep slopes>25 °φ Estimated on the agricultural cpopulation alone, the per capita cultivated area is 1.2 mu and per capita tood production 409 kg.Features ot serious water and miss erosion are seldom out of sight.Land deterioration is too obvious to escape the notice of even the lay mind. There is little room for the expansion of conventional agriculture.A proposal under consideration is chiefly the construction of contour terraces with stones on selected sites with slopes up to 25° either cultivated or nonculti vated. According to informatiom available and field observation in a few localities, this seems acceptable in soms cases.Some examples have even experienced unusually heavy storms and severe droughts.However,furrther studies are necessary for assessment with respect to ecological and economic sustainability of terraces in recent years and of the sites for further construction.The search of alternatives for cheaper sustainale utilization of the sloping land is suggested. This includes in the main ths establishment of contour barrier hedgerows composed of woody plants and contourherbaceous strips to shape terraces in between and the use of the litter for plant. production to meet the demands of the local population and accessible markets. On the terraces contour planting contour tillage, minimum tillageand soil surfae mulch are called to provide additional protection against water eeosion and proper selection of plants, appropriats planting patterns aad and rotation for the replenishment of nutrients and the maintaince and improvement of soil physical properties Cost-effeetivensss analysis should be included in the design of hedgerows and herbaceous strips, waereas extended cost-benefit analysis plays the role in planning the terrace utilization. Since the terraces result from hedgerows and herbaceous strips, the whole slope beginning from the water-divide down to the foot should be taken as a unit for cost-benefit analysis. To evalue the off-site benefits, it is more practical to encompass a watershed composed of several slopes.There are tracts of land not amenable for terrace making terraces with hedgerovs and herbaceous strips because of slopss too steep or soils too thin For much of these, utilization and amelioration are still possible provided that the local demands for fuel, fertilizer and other products are satisfied otherwise. Some plants commonly found in the region are adaptable to such adverse habitats as stony soils and rocky surface with cracks and does not fail to supply some useful products and help to control water and mass erosion.More will be found in further investigations.

Key words: Agriculture, Three Gorges Region