一、自然概况陝北米脂县杜家石沟农业社,位于无定河中游,孟岔沟支流中段,屬于黃土丘陵沟壑区,海拔高1000米左右,地形錯縱复杂,支以离破碎。深約二百米以上的沟壑,每平方公里內就有5—6条,大小不等的丘陵山峁30～40个。耕地坡度多在10～40度之間,农地几乎全部都在这些沟壑山岭中。 First, the natural profile Dujia Shigou agricultural cooperatives in Mizhi County, northern Shaanxi Province, located in the middle reaches of Wuding Ditch, located in the middle reaches of the Wuchagou, belongs to the loess hilly and gully area, about 1000 meters above sea level, the terrain is wrong and complex, branches to fragmentation. Deep about 200 meters above the gully, there are 5-6 per square kilometer, ranging from the hilly mountain ridge 30 ~ 40. Cultivated land is mostly between 10 and 40 degrees, almost all of which is in these gully mountains.