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农田防护林带在林网中存在着“近胁地,远受益”的客观现实。林带树木根系吸收大量水分、养分,树冠遮荫,使林带近缘的土壤变得瘠薄。人们把这种影响叫做“胁地”,造成农作物减产。而那些离林带较远处,由于林带防风、固沙,调节小气候,较好地维持了生态平衡,又不受林带树木争水、争肥、争阳光的危害,农作物能大面积增产。在大包干生产责任制实行以前,大部分农田林网属于一个经济核算单位,对于一个生产队来说,林网内的受益面积远远超过林胁地面积,一般为九与一之比,增产效益仍是显著的,但是,农业实行大包干责
Farmland shelterbelts in the forest network there is “nearly threatened, far benefit,” the objective reality. Forest tree roots absorb large amounts of water, nutrients, canopy shade, so that the soil near the forest barren. This effect is called “threatening” and results in a reduction of crops. Those far away from the forest belt, due to windbreaks, sand fixation, climate regulation, better maintain the ecological balance, but also from the forest tree water, fight fertilizer, the sun, the crop can be large-scale production. Before the implementation of the responsibility system for producing large parcels, most farmland forest nets belonged to an economic unit of account. For a production team, the benefit area in forest nets far exceeded the area threatened by forest land, which is generally the ratio of 9 to 1, Benefit is still significant, however, agriculture is responsible for big packages