Effects of ridge-furrow rainwater harvesting with maize straw biochar on fodder yield and water use efficiency of alfalfa in semiarid regions of China

Purpose On a global scale, water resources are under intense stress due to climate change. It is, therefore, crucial to understand how in situ water harvesting techniques and the addition of soil organic amendments such as biochar affect soil properties and productivity of alfalfa ( Medicago sativa L.) to inform wider adoption by farmers. Methods To contribute to this research area, an experiment was conducted at the Anjiagou Catchment experimental station during the 2020 to 2021 alfalfa growing seasons. The experimental design was a split-plot design with three replications. The main treatment was maize straw biochar, and the sub-treatment was ridge-furrow rainwater harvesting. The biochar treatments were 30 t ha −1 and 0 t ha −1 , and the rainwater harvesting methods were flat planting (FP), tied-ridging (TR), and open-ridging (OR). Results In 2020, soil temperature in the TR treatment decreased by 6.54 and by 4.08% for the OR treatment compared with the FP. In 2021, soil temperature decreased by 3.87 and 0.87% in the TR and OR, respectively, compared with the FP. In general, the integration of rainwater harvesting systems and maize straw biochar amendment significantly ( p < 0.05) increased alfalfa fodder yield during the 2-year growing seasons investigated. Mean soil desiccation increased by 55.16% in the no-biochar–amended treatment compared to 52.58% for the biochar-amended soils. Overall, the highest net economic benefit throughout the 2 years of alfalfa cultivation was recorded in the TR and OR treatments with maize straw biochar addition. Conclusion In both experimental years, ridge-furrow rainwater harvesting-planting with maize straw biochar produced the highest alfalfa fodder yield than the FP treatment and the no-biochar–amended soil. An important contribution of this work to smallholder forage farming is the evidence demonstrating the positive effects of maize straw biochar in ridge-furrow rainwater harvesting system on alfalfa fodder yield, water productivity, and economic benefit in rain-fed agriculture.