Aim and methods Staged water shortages and excessive nitrogen application lead to a decline in crop yield, and nitrogen loss, waste of resources and environmental pollution. In order to explore the appropriate water management in humid areas and to determine an e cient nitrogen rates for maize, we conducted a eld experiment (2020-2021), with ve nitrogen rates N0, N150, N200, N250, N300 (0, 150, 200, 250, 300 kg ha -1 ) under different water conditions (rainfed and irrigated).Conclusion Consequently, under the irrigated conditions, the soil organic matter (SOM), microbial biomass carbon (MBC), dry matter accumulation and grain yield were signi cantly (P < 0.05) increased by 8.06%, 15.50%, 11.43% and 13.86%, respectively, compared with the rainfed conditions. And the total nitrogen (TN), nitrate nitrogen (NO 3 --N), ammonia nitrogen (NH 4 + -N) decreased signi cantly by 4.38%, 8.28%, 13.21%, respectively. Furthermore, compared with other nitrogen rates, N250 and N300 combined with irrigated signi cantly (P < 0.05) increased soil carbon and nitrogen content, dry matter accumulation and grain yield. However, N250 and N300 displayed no signi cant difference (P > 0.05) in TN, NO 3 --N, NH 4 + -N, SOM, MBC, dry matter accumulation and grain yield. Moreover, under the irrigated conditions, when the nitrogen rates increased more than 250 kg ha -1 , the nitrogen use e ciency decreased. Hence, application of nitrogen rates of 250 kg ha -1 under irrigated conditions is the best choice to increase grain yield, improve nitrogen use e ciency, and ensuring safe and e cient production in maize.