以１９８３～１９９２年的田间试验结果和室内分析资料为依据，探讨了黄土丘陵区长期施用氮磷肥效应及平衡特征。结果表明：产量对长期施肥反应明显，不同作物在不同土地类型上，均以配施效果好而稳定。作物吸Ｎ，Ｐ量与产量规律一致，但随施肥时间延长，吸Ｎ，Ｐ量呈递减趋势。平衡结果表明：Ｎ，Ｐ配施土壤Ｎ素亏损，川地Ｐ素盈余，有机无机配合，Ｎ素均有盈余。坡地由于水土流失，除ＭＮＰ处理外，土壤Ｐ素均处亏损状态。由此得出，坡地应控制水土流失，提高土壤肥力 Based on the field test results and indoor analysis data from 1983 to 1992, the effects of long-term application of nitrogen and phosphorus on the hilly Loess Plateau and their balance characteristics were discussed. The results showed that the yield responded to the long-term fertilization obviously. Different crops had good and stable effect on the different land types. The amount of N and P uptake in crop was consistent with the yield, but the N and P uptake decreased with the extension of fertilization time. The results of the balance showed that N and P combined with N deficit in soil, P surplus in Sichuan area, organic and inorganic complex, N surplus. Because of water and soil loss on sloping land, except for MNP treatment, P-deficient soil was in a loss state. It is concluded that the slope should control soil and water loss and improve soil fertility