Following legume establishment, microbial and chemical associations facilitate improved productivity in degraded grasslands

Backgrounds and aims Mowing and P-fertilization enhance legume seedling establishment, assisting in successful restoration of degraded grasslands. Legume establishment may influence soil chemical compounds and soil microbial assemblage to facilitate legume productivity. We aim to better understand these complex plant-soil-microbial interactions to improve grassland productivity following overgrazing. Methods We conducted a 3-years Medicago falcata reseeding experiment was in semi-arid meadows, assessing responses of aboveground plant biomass, soil chemical compounds, and soil microbial community composition. Reseeded plots were mowed and/or P-fertilized. Results Application of both management practices increased grassland biomass compared with all other combinations. Soil chemical diversity predicted fungal alpha diversity, and fungal alpha diversity positively correlated with aboveground biomass. Our results indicate reseeded alfalfa directly altered bulk soil chemical compounds with subsequent alterations in grassland microbial communities. Soils contained chemical compounds with antifungal properties that indirectly improved grassland productivity via antagonism to pathogenic fungi. Furthermore, we found three specific compounds (5-methyltridecane, pentatriacontane, and N-tridecane) reduced microbial diversity. Conclusions Here we demonstrate soil chemical compounds play an important role in shaping beneficial microbial communities to improve grassland biomass. These results may help direct beneficial soil microbial community composition through improved grassland management practices.