The Synergistic Effect of Biochar and Microorganisms Greatly Improves Vegetation and Microbial Structure of Degraded Alpine Grassland on Qinghai–Tibet Plateau

Abstract

The attenuation of soil organic carbon and the destruction of soil microbial structure are common manifestations of grassland degradation. The addition of exogenous organic carbon and microorganisms may be an effective way to quickly restore degraded grassland, but corresponding evaluations are still rare. We investigated the effects of effective microorganisms (EM) and biochar addition on vegetation biomass, microorganisms and soil properties in degraded alpine grassland. The treatments included a control (no biochar or EM addition, CK), EM addition (250 mL m−2 EM, M), biochar addition (4.00 kg m−2 biochar, C) and a mixture of biochar and EM (4.00 kg m−2 biochar and 250 mL m−2 EM, C+M). C, M and C+M rapidly increased vegetation biomass, soil organic carbon (TOC), total nitrogen (TN), available nitrogen (NH4+-N, NO3−-N), available phosphorus (AP), total microbial biomass (MB), bacteria and fungus biomass in the soil, and also altered the microbial community structure. The content of soil nutrients in the C treatment was the highest, followed by C+M. The vegetation biomass and microbial biomass were the greatest in the C+M treatment, and increased by 101.04~198.52% and 22.14~45.41%, respectively. C+M can also enhance the presence of saprotrophic fungi, thereby facilitating the augmentation of both plant and soil nutrients. Overall, the biochar combined with EM addition had a synergistic effect on the restoration of degraded alpine grasslands.