Enhancing soil health and microbial resilience with organic fertilization in semi-arid Astragalus ecosystems.

Organic fertilization, particularly manure (MF) and compost (CF), is an effective and sustainable method for improving soil health. However, their impacts on soil bacterial communities and nutrient cycling in semi-arid Astragalus systems remain unclear. In this study, we investigated the effects of MF and CF on soil properties and bacterial communities over two years, analyzing 36 soil samples from two depths (0-20 cm and 20-50 cm). Bacterial composition was determined using high-throughput 16S rRNA sequencing, and the relationships between microbial communities and soil properties were explored using network analysis, Pearson correlations, and Mantel tests. Both amendments significantly improved soil properties (p < 0.05), with the mean soil quality index (SQI) increasing from 0.18 in the control to 0.50 with CF and 0.55 with MF. The relative abundances of Proteobacteria and Bacteroidota increased by 32-33 % and 8.6-10.8 %, respectively, compared to the control. Average network modularity and density were higher in MF (0.64, 0.335) and CF (0.58, 0.34) compared to the control (0.53, 0.32), indicating improved ecosystem resilience. Several genera, including Lysobacter, Nitrospira, and Pedobacter, showed positive correlations (p < 0.05) with key soil traits, suggesting their roles in nutrient cycling. Our results demonstrate that manure and compost fertilization not only enhance soil quality and microbial diversity but also strengthen ecosystem resilience. These findings suggest incorporating organic amendments, such as manure and compost, rather than chemical fertilizers, to enhance soil quality, promote sustainable agriculture, and support ecosystem stability in semi-arid farming systems.