Profit and loss of nutrients in crop-fruit ecosystems
农果复合系统营养物质的盈亏平衡特征

The analysis on the balance of nutrient's profit and loss in crop-fruit ecosystems of three villges in middle-south Loess Plateau showed that fertilization was the main input of nutrients,of which,chemical fertilizer occupied a larger proportion,while organic manure was relatively insufficient.The quantity of N,P and K spent in interior circulation was far less than that exported from the ecosystem.The ratio of nutrient's output and input in three test villages was differed,but all at a low level.