Optimizing nitrogen fertilization and irrigation strategies to balance agroecosystem services in the wheat-maize double cropping system: A 21-year field study

Context: Conventional agricultural practices, characterized by elevated fertilization and irrigation, have led to a range of negative consequences. Reducing and adjusting water and fertilizer usage is essential for achieving sustainable agricultural development. Objective: This study aims to investigate the trade-offs between economic profitability and multiple ecosystem services under reduced irrigation and fertilizer practices, with a particular focus on their long-term impacts. Methods: Here, a 21-year field experiment was used to assess the effects of 7 different fertilization rates (85-605 kg N ha-1) and irrigation levels (0-525 mm) on provisioning, economy, supporting and regulating services, along with their sustainability index and trade-offs, within a wheat-maize double cropping system. The wheat and maize yields were evaluated during 2019-2023 and the soil samples were collected in 2023. Results: A 9 % reduction in fertilization (from 555 to 505 kg N ha-1) and a 16.7 % reduction in irrigation (from 450 to 375 mm) led to a slight decrease in grain yield but did not compromise economic performance due to lower inputs costs. Furthermore, reducing fertilizer by 9 % and irrigation by 16.7 % enhanced soil quality by 8.11 % and significantly decreased nitrogen leaching by 35.9 %, minimizing environmental pollution. The sustainability index increased with higher fertilization and irrigation, reaching its peak at the optimal levels (505 kg N ha-1 and 375 mm) with a value of 2.38, remaining stable for the rest of the treatments. This represents a 3.09 % increase compared to conventional practices. These reductions in fertilization and irrigation may help reconcile ecosystem sustainability with economic profitability. Conclusion: Overall, the optimal inputs for the wheat-maize cropping system were determined to be 505 kg N ha-1 for nitrogen application and 375 mm per year for irrigation, achieving a balance win-win outcomes for both economy and environment objectives. Implications: This study provides a viable approach to sustainable food production by demonstrating the advantages of environmentally conscious crop management practices through optimized fertilization and irrigation strategies.