Low-temperature-fermented straw compost promotes alfalfa growth and imparts stress tolerance

The physicochemical properties of soil have a significant impact on plant growth, and fertilizers that improve soil quality play a crucial role in promoting crop development. Abandoned crop straw, once composted and converted into organic fertilizer, is an important resource for agricultural production. However, the mechanisms by which straw compost regulates plant growth remain incompletely understood. In previous work, we demonstrated that low-temperature–fermented straw compost significantly promoted the growth and yield of rice. Building on this, the present study again focused on the effect of low-temperature-fermented straw compost on alfalfa growth. We found that applying straw compost significantly accelerated alfalfa growth and improved multiple physiological indicators. At the same time, it regulated the expression of key genes in metabolic pathways, secondary-metabolite synthesis pathways, and plant hormone signal transduction. In addition, straw compost improved soil pH, significantly increased soil organic matter content, and enhanced both the activities of certain soil enzymes and the abundance of soil microorganisms, achieving the dual goals of optimizing soil and promoting alfalfa growth. Overall, the study demonstrates that low-temperature-fermented straw compost exerts a broad-spectrum promoting effect on crop growth and provides an important theoretical basis for promoting low-temperature straw fermentation technology and the application of straw composting in agricultural and animal husbandry production.