Effects of Ridge-Furrow Rainwater Harvesting with Biochar-Soil Crust Mulching on Soil Properties, Nutrients, and Alfalfa Fodder Yield in a Semiarid Agroecosystem

Purpose Alfalfa ( Medicago sativa L.) production is adversely impacted by surface runoff and drought stress. This is particularly true for alfalfa planted in semiarid areas. Therefore, the development of erosion-tolerant management practice is crucial. Methods A study was carried out in a completely randomized design, with 4 treatments (3 straw biochar application rates + flat planting (FP) as control), and 3 straw biochar application rates of 0 × 10 4 (no biochar (NB)), 3 × 10 4 (single straw biochar-soil crust (SSB)) and 6 × 10 4 kg hm −2 (double straw biochar -soil crust (DSB)), respectively. Results Mean runoff efficiency in SSB was 16.58% compared to no-biochar treatment (20.14%), and in DSB was 14.57%. From 2017 to 2020, NB had the highest R 2 value for the variation between runoff and rainfall and DSB had the lowest R 2 value. In comparison to FP treatment, application of biochar to SSB significantly ( p < 0.05) reduced runoff and increased soil water storage. The difference in soil water storage between pre-sowing and post-harvesting during alfalfa growth season increased on average by 15.69% with NB practice compared to FP, and by 11.79% and 7.58% with SSB and DSB practices, respectively. The mean weight diameter (MWD) in SSB treatment was higher than that in DSB treatment, although soil nutrients were increased in the following order: DSB > SSB > NB > FP. After post-harvest, average yields in NB, SSB, and DSB treatments were higher than those in FP treatment by 8.16%, 25.71%, and 18.31% respectively. With a mean yield of 8607 kg ha −1 , SSB significantly increased alfalfa yield across all years. Conclusion Evidence from the four-year experiment suggested that biochar-soil crust made from a single straw significantly reduced surface runoff, increasing soil water storage, soil aggregate stability, soil nutrients, and alfalfa fodder yield. Based on our research, we advise using single straw biochar-soil crust to boost alfalfa fodder production in semi-arid regions.