Effects of soil salinity on nitrogen fate and nitrogen use efficiency of maize (Zea mays L.) fieldin the Hetao Irrigation District of China

Background and Aims Soil salinity is a critical factor influencing nitrogen (N) dynamics and crop productivity in arid and semi-arid regions. This study aims to elucidate the effects of different soil salinity levels on nitrogen fate and nitrogen use efficiency in maize ( Zea mays L.) fields under arid environmental conditions. Methods Two-year field experiments were conducted on three salinized soils to cultivate maize. Maize growth parameters (e.g., plant height, leaf area index, yield, nitrogen use efficiency, and water use efficiency) and nitrogen losses (including N ₂ O, NH ₃ , and nitrogen leaching) were monitored within the agroecosystem. Based on these data, the apparent nitrogen balance was analyzed in an agroecosystem under salinity stress. Results Salinity stress significantly increased cumulative N ₂ O emissions (56%–183%) and NH ₃ volatilization (65%–81% under the light salinity stress and 2%–19% under the moderate salinity stress) compared to the non-saline conditions (NS). Nitrogen leaching increased by 97%–249% and 79%–111% under the light salinity stress (LS) and the moderate salinity stress (MS), respectively. Salinity stress reduced the nitrogen deficit in agroecosystems, and decreased maize biomass, grain yield, and nitrogen use efficiency, leading to a significant decline in the partial factor productivity of nitrogen fertilizer (5.65%–30.13%). Conclusion Soil salinity significantly increases nitrogen losses through enhanced N ₂ O emissions, NH ₃ volatilization, and nitrate leaching, while salinity stress alters nitrogen balance by reducing nitrogen deficit in farmland ecosystems. Additionally, salinity-induced nitrogen losses substantially reduce maize yield. These findings could provide reference for proper feralization scheduling and mitigation of greenhouse gas emissions in arid salt-affected farmland.