Assessing trade-offs between peanut productivity, economic returns, and soil sustainability under reduced nitrogen fertilizer in a green manure–peanut rotation: A CRITIC–TOPSIS approach

Integrating non-legume green manure into peanut rotations offers a promising strategy to enhance resource use efficiency and sustain crop productivity. However, uncertainties remain regarding the optimal management of green manure biomass, its interaction with nitrogen (N) fertilizer requirements, and related economic outcomes. This study evaluated the agronomic and economic trade-offs between incorporating versus removing ryegrass biomass under varying N application rates within a ryegrass–peanut rotation system. A two-season field experiment was conducted using a split-plot design. Main plots comprised two ryegrass management strategies—biomass incorporation as green manure (H) and biomass removal for forage use (R)—while subplots consisted of four N application rates (120, 90, 60, and 0 kg N ha -1 ), resulting in eight treatment combinations (HN0, HN60, HN90, HN120, RN0, RN60, RN90, RN120). Effects on soil properties, peanut yield, nitrogen use efficiency (NUE), and economic performance were assessed. A multi-criteria decision-making approach using CRITIC–TOPSIS was employed to comprehensively evaluate and rank the outcomes. Biomass incorporation significantly improved soil physical and chemical properties over residue removal, reducing bulk density and increasing total N (TN), soil organic carbon (SOC), and enzyme activities (urease, invertase, cellulase). While reduced N inputs decreased yields overall, the HN90 treatment (25% N reduction) produced kernel yields statistically comparable to HN120, the full-N treatment. HN90 also improved kernel agronomic NUE by 45.6% over HN120 and enhanced the partial factor productivity of applied N. Economically, R treatments incurred higher costs due to forage harvesting but generated stable revenue, resulting in higher net returns for RN120. Nevertheless, CRITIC–TOPSIS and sensitivity analyses consistently identified HN90 as the optimal strategy, balancing yield, efficiency, and sustainability. These findings offer a robust basis for refining nitrogen management in peanut-based rotations, guiding efforts to enhance resource efficiency, profitability, and soil health in pursuit of more sustainable cropping systems. • Green manure improved soil fertility and enzyme activities under reduced nitrogen. • Green manure maintained high yields and boosted nitrogen use efficiency under reduced nitrogen. • The CRITIC–TOPSIS evaluation and sensitivity analysis identified green manure incorporation with a 25% nitrogen reduction as the most sustainable and profitable strategy.