山区群众有这样的经验:在山坡上开垦一块灌木草甸地,第一年开荒后,土壤疏松,不耐雨水冲刷,泥土随雨水冲走的较多,以后逐年减少,终至把表层肥沃的泥土都冲走了,剩下的是麻骨石土,或母质土,不能耕种,成了弃而不顾的撩荒地。常 The mountainous people have the experience of reclaiming a shrub meadow on the hillside. After the first year of land reclamation, the soil is loose and irresoluble with rainwater and the soil is washed away with the rainwater. Since then, it has decreased year by year, finally turning the surface fertile The soil is washed away, and the rest is the brown soil, or the mother of the soil, can not cultivate, abandoned and ignored abandoned land. often