Mitigating Carbon and Nitrogen Footprints While Enhancing Ecosystem Economic Benefits via Strategic Application of Slow-Release Fertilizer and Mulching

Dryland farming on the Loess Plateau faces significant challenges due to water scarcity and low nitrogen use efficiency. Although conventional urea sustains crop yields, it is associated with elevated greenhouse gas emissions and nitrogen losses. Despite growing interest in both slow-release fertilizers and plastic mulching, their environmental footprints remain insufficiently evaluated. This study, therefore, aimed to identify a management strategy that maximizes productivity while minimizing environmental impacts. Using a life-cycle assessment (LCA) framework, we compared four cultivation strategies, flat cultivation with urea (NU), flat cultivation with slow-release fertilizer (NS), mulching with urea (PU), and mulching with slow-release fertilizer (PS), each at nitrogen rates of 125, 225, and 325 kg ha−1. The results demonstrated that PS reduced the carbon footprint per unit of net ecosystem economic benefits (NEEB) by 3.74–27.86% and the nitrogen footprint per unit of NEEB by 10.48–47.41%. At 225 kg ha−1, PS increased grain yield and NEEB by 7.40% and 9.87%, respectively, compared to 125 kg ha−1. Compared to 325 kg ha−1, the 225 kg ha−1 rate improved energy use efficiency by 19.81% while reducing carbon emissions, carbon, and nitrogen footprint per unit of NEEB by 10.29%, 14.36%, and 24.47%, respectively. In conclusion, mulching combined with slow-release fertilizer at 225 kg ha−1 represents a balanced and regionally appropriate strategy, achieving strong agronomic performance alongside reduced environmental costs and improved economic returns.