农田复种指数的提高,夺走了土壤中的大量养分,因得不到相应补偿,土壤肥力下降.为了维持和提高农作物的产量,不得不增加化肥投入,从而形成了生产中提高产量——增加化肥投入量——再提高产量——再增加化肥投入量的恶性循环,导致了生产成本高,经济效益低的后果,这是当前种植业生产中一个带普遍性的问题,以滕县1976～1986年统计数字为例,全县1976年复种指数为160.0%,1986年增至173.3%,而有机肥 The improvement of farmland multiple cropping index has taken away a large amount of nutrients from the soil and the soil fertility has not been reduced due to lack of corresponding compensation. In order to maintain and increase the yield of crops, the input of fertilizers has to be increased so as to increase the output in production Fertilizer input - and then increase production - and then increase the vicious cycle of fertilizer inputs, resulting in high production costs, low economic benefits of the consequences, which is a common problem in the current crop production, to Teng 1976 ~ 1986 statistics, for example, the county in 1976 the crop index was 160.0% in 1986 to 173.3%, while the organic fertilizer