Rainfall Enhancement Impacts on Soil pH in Chinese Grasslands: A Study of Precipitation and Temperature Effects

Rainfall enhancement significantly increased soil pH by 0.9% in areas with annual precipitation less than 200 mm, and by 2.3% in areas with precipitation between 200-400 mm. In areas with annual precipitation greater than 400 mm, both rainfall enhancement and reduction had no significant impact on soil pH. Rainfall enhancement significantly increased soil pH by 6.7% in areas with an average annual temperature below 0℃, while in areas with an average annual temperature above 0℃, both rainfall enhancement and reduction had no significant impact on soil pH. By increasing vegetation cover and reducing species richness and underground biomass, rainfall enhancement indirectly increased soil C and N content, significantly improving soil pH in Chinese grasslands. In areas with MAP<400 mm, rainfall enhancement significantly reduced soil pH in Chinese grasslands mainly through its impact on soil C, N, and P content. This study can provide reference for the management of grassland ecosystems in response to global precipitation changes.