Combination of nitrogen-fixing bacteria and mycorrhizal fungi promotes Leymus chinensis growth and bioremediation of degraded grasslands in semi-arid regions

Accelerated grassland degradation due to global climate change and intensified human activities necessitates green and sustainable ecological restoration measures. Microbial and organic fertilizer composites have shown positive effects in agricultural soil improvement. However, the effects on soil nutrient cycling and plant growth of microbial inoculants alone or in combination with organic fertilizers on the multifunctionality of natural ecosystems remain unclear.

This study explores the effects of Bacillus subtilis, Azotobacter salinestris, and Claroideoglomus lamellosum (added alone or in all possible combinations), applied in conjunction with organic fertilizers at different inoculation levels on the physicochemical properties of degraded soil, microbial factors, and Leymus chinensis plant biomass through pot experiments.

Results indicate that combining organic fertilizers with B. subtilis, A. salinestris, and C. lamellosum enhances soil nutrient availability. Compared to single organic fertilizer treatments, all mixed inoculation schemes increased nutrient uptake. The combined inoculation of A. salinestris and C. lamellosum is most effective, resulting in a remarkable 465% increase in belowground biomass and significantly enhancing soil nutrient content, particularly with increases of 247% in NH + 4-N and 348% in NO- 3-N. Soil enrichment with external nutrients can influence the strength of their interactions with different factors.

The study demonstrates that co-inoculation of bacteria and fungi has a synergistic effect on increasing plant biomass and soil nutrient availability. This provides essential ecological theories and practical scientific evidence for using microorganisms to improve the ecological functions of degraded grasslands, maintain soil health, and ensure the sustainable development of grasslands.