Oat/soybean strip intercropping benefits crop yield and stability in semi-arid regions: A multi-site and multi-year assessment

Context: Intercropping plays a crucial role in promoting agricultural sustainability and offers an alternative way to enhance crop production and ensure food security. However, the yield benefits and stability of oat/soybean intercropping have rarely been assessed across multiple sites and years, especially in semi-arid regions with low and unevenly distributed precipitation. Objective: This study aimed to investigate the yield performance, yield stability, and economic benefits of oat/ soybean strip intercropping through multiple sites and years of field experiments. Methods: A three-year field experiment (2019-2021) with a completely randomized block design was conducted at three representative sites in semi-arid regions of China (i.e. Wulanchabu, Youyu, and Zhangjiakou). Each experiment included oat/soybean intercropping and corresponding monoculture with four replicates. Land equivalent ratio, yield stability, and economic income were compared between intercropping and monoculture. Results: Over the three years, intercropping led to a substantial increase in oat yield, ranging from 21.7 % to 47.6 %, albeit accompanied by a reduction in soybean yield by 14.6-26.5 %, compared to corresponding monoculture. The results revealed a notable improvement in land use efficiency across all three sites with a mean land equivalent ratio (LER) of 1.12. Further analysis demonstrated that the yield enhancement of intercropped oat was evident not only in the border rows (2.21 times of monoculture) but also in the inner rows (1.13 times of monoculture), highlighting their combined contributions. Moreover, intercropping produced 5.2 similar to 9.4 % higher net income on average across multiple sites and years. Additionally, intercropping exhibited 5.5 similar to 62.6 % greater temporal yield stability compared to monoculture at two of three sites, and the temporal yield stability was positively correlated with crop yield and net income. Conclusions: Oat/soybean strip intercropping emerges as a promising agronomic strategy to boost crop production while preserving relatively higher yield stability, thereby enhancing farmers' economic income across diverse semi-arid regions in China. Implications: Our findings demonstrated the feasibility of the oat/soybean strip intercropping in semi-arid regions and evaluated its over-yield mechanisms, which is significant to agricultural sustainable development.