Mixed cropping of common vetch and hairy vetch enhances system productivity and economic returns in a wheat-based double-cropping system in an arid irrigated region

In arid irrigated regions with limited growing seasons, establishing sustainable post-wheat ( Triticum aestivum L.) cropping systems is crucial for agricultural intensification and soil conservation. This study aimed to evaluate and identify an optimal post-wheat cropping system that enhances biomass production, soil quality, crop performance, and economic returns under arid conditions. A seven-year field experiment (2018–2024) was conducted in northwestern China, comparing seven systems after spring wheat harvest: common vetch ( Vicia sativa L.)/hairy vetch ( Vicia villosa Roth.) mixture (W-CV×HV), common vetch/rapeseed ( Brassica napus L.) mixture (W-CV×R), hairy vetch/rapeseed mixture (W-HV×R), sole common vetch (W-SCV), sole hairy vetch (W-SHV), sole rapeseed (W-SR), and a fallow control (W-W). The W-CV×HV system demonstrated exceptional performance. It produced the highest biomass, with increases of 14.3–23.9 % over other mixtures, and enhanced crude protein yield by 13.7–44.4 %. This advantage was supported by strong interspecific facilitation (LER=1.18). This system significantly improved subsequent wheat performance, increasing grain yield by 2.7–8.8 % and yield stability by 66.9 % compared to sole legume cropping. After seven years, W-CV×HV most substantially improved soil quality, increasing soil organic matter and total nitrogen while reducing pH, EC, and bulk density. Economically, the system achieved 9.8–14.1 % higher monetary value than other cropping systems. The legume-legume mixture of common vetch and hairy vetch represents a superior post-wheat cropping system, surpassing traditional fallow and single-species systems in agronomic, ecological, and economic performance. This system provides a sustainable alternative for integrated agricultural intensification in arid environments, contributing to soil health stabilization, yield resilience, and improved farm profitability. Mixed cropping of common vetch and hairy vetch enhances system productivity and economic returns in a wheat-based double-cropping system of an arid irrigated region. • Common vetch/hairy vetch mixture increases biomass by 14.3–23.9 % and crude protein yield by 13.7–44.4 %. • The post-wheat mixed cropping system exhibited interspecific facilitation, with a land equivalent ratio (LER) of 1.18. • Soil quality significantly improves with increased organic matter and reduced pH and bulk density. • Subsequent wheat yield enhances by 2.7–8.8 % with 66.9 % higher yield stability. • The system achieves 9.8–14.1 % higher economic returns while reducing fertilizer dependency.