Irrigation-driven trade-offs between yields and nitrogen losses in global major crop production

Irrigated agriculture is vital to global food production, yet its effects on the trade-offs between crop yields and nitrogen (N) losses—including ammonia volatilization, nitrous oxide emissions, and N leaching and runoff—remain insufficiently understood at the global scale. This study focused on three major crops (maize, rice, and wheat) using the DNDC (DeNitrification–DeComposition) model to simulate the spatiotemporal variations in yield-scaled N losses under irrigated and rain-fed conditions worldwide from 1981 to 2020. Scenario analysis was further conducted to quantify the role of irrigation in mitigating yield-scaled N losses. Results indicated a general increase in the contribution of irrigated systems to global maize, rice, and wheat production during 1981–2020, along with a possible tendency toward higher N losses from maize and wheat. High-value regions of yield-scaled N losses under both irrigated and rain-fed systems were concentrated in India, Pakistan, Bangladesh, and China. Overall, irrigation reduced yield-scaled N losses relative to rain-fed systems, with particularly pronounced reductions for maize in Central and West Asia and the western USA, for wheat across China, Europe, and the USA (regions characterized by arid or semi-arid climates), and for rice in Southeast Asia. These findings advance our understanding of how irrigation influences the balance between crop productivity and environmental impacts, and provide scientific evidence to support integrated water management, climate change mitigation, and global food and environmental security.