Enhanced nitrogen imbalances in agroecosystems driven by changing cropping systems in a coastal area of eastern China: from field to watershed scale

摘要: Agricultural activities exacerbate nitrogen (N) imbalances in the agroecosystem by disturbing N inputs and outputs, yet influence of changes cropping systems on balance agroecosystems remains unclear. In this study, at field scale, we calculated four systems, (1) traditional crops with crop rotation (G–G), (2) vegetables (V–G), (3) vegetable (V–V), (4) greenhouse (GHV); then analyzed from 1995 to 2015 balances sub-watersheds Dagu River. The results indicate that were higher GHV, V–V, V–G than G–G, due significantly fertilizers lower use efficiency (NUE) cultivation compared crops. Driven economic benefits between 2015, V–G, GHV replaced G–G a considerable number areas sub-watersheds. These resulted an increase 109.9–170.1% 2015. entire watershed, total surplus contribution increased 39.3% 79.1% findings suggest contributed risk pollution agricultural production. Thus, there should be focus management control loss lands.