Resumen
Systematic evaluation of nitrogen (N) application in multi-crop production and its environmental impacts are of great significance for sustainable development of agriculture. Previous studies have focused on the evaluation of grain crops at the national and provincial levels, but ignored the county scale. Here, we evaluated the N rate, N use efficiency (NUE), N surplus, and greenhouse gas (GHG) emissions from the production of multiple crops including rice, wheat, maize, soybeans, tea, fruits, and vegetables at the county level of Fujian Province, China. The results showed that the N rates, N surpluses, and GHG emissions were generally higher, and NUEs were generally lower in the southern and southeastern coastal counties of Fujian Province, while the counties in the north and west had the opposite distribution trends. The N input and its negative environmental impacts for grain crops were generally lower than those for cash crops. The average NUE of all crops in Fujian Province in 2014 was 52.31%. The N input and N surplus for fruits accounted for 43.95% and 46.69% of those in the whole province, respectively. The evaluated framework we proposed in this study can be widely applied in the systematic evaluation of N input and its environmental footprints at the county scale for regions with multi-crop production.