Yield Performance, Resource-Use Efficiency, and Economic Profitability from Adopting Soybean-Based...

Legume intercropping is a productive diversification strategy that can improve land-use efficiency and farm profitability, particularly for smallholders. However, its adoption remains limited in resource-intensive farming systems because crop-specific agronomic performance, input-use implications, and economic feasibility are not well documented under farmer-field conditions. This four-year field study (2021-2024) evaluated four sole cropping systems (sole cotton, sole maize, sole sugarcane, and sole soybean) and three additive soybean-based intercropping systems (cotton/soybean, maize/soybean, and sugarcane/soybean) under arid-irrigated conditions. Crop yield, dry matter accumulation, nutrient uptake, land equivalent ratio for land (LER_L), land equivalent ratio for nitrogen (LER_N), land equivalent ratio for phosphorus (LER_P), economic profitability, and labor requirement were assessed. On average, across the four study years, intercropped cotton, maize, and sugarcane produced 80%, 74%, and 88% of their respective sole-crop yields, while intercropped soybean produced 72%, 59%, and 83% of sole-soybean yield in cotton/soybean, maize/soybean, and sugarcane/soybean intercropping systems, respectively. At the system level, the total LER_L, LER_N, and LER_P values ranged from 1.33 to 1.71, 1.35-1.68, and 1.25-1.64, respectively, indicating resource-use (land and nutrients) advantages of intercropping compared with sole cropping. Based on these observed LER_N and LER_P values, soybean-based intercropping showed theoretical potential to reduce nitrogen and phosphorus fertilizer requirements by 26-40% and 20-39%, respectively; however, these estimates should be interpreted as potential input-economy indicators rather than experimentally validated fertilizer reductions. Economically, intercropping increased net income by ≈29-154% and generated 18-28% more labor demand than the corresponding sole systems, with sugarcane/soybean showing the highest net income (2937 USD ha^-1). Overall, additive soybean-based intercropping, particularly cotton/soybean and sugarcane/soybean systems with greater temporal niche differentiation, improved land productivity, nutrient-use efficiency indicators, and farm profitability under the tested arid-irrigated conditions. Further multi-location studies with actual reduced-fertilizer treatments are needed to validate fertilizer-saving potential and broader applicability.