To investigate the effects of restoration measures on degraded grasslands in the typical steppe of Inner Mongolia, two restoration treatments—enclosure (EN) and enclosure with additional bio-organic fertilizer application (EF)—were established with moderately grazed degraded grassland as the control (MG). The impacts of these measures on vegetation community characteristics and soil physicochemical properties were systematically analyzed, and the post-restoration ecological benefits were quantitatively evaluated using an assessment system. The results showed that (1) over the two experimental years, both EN and EF treatments improved vegetation community characteristics and soil physicochemical properties, with the overall restoration effect ranking as EF > EN > MG; (2) compared with the first experimental year, the restoration of plant and soil characteristics was more significant in the second year; (3) ecological benefit analysis showed that the Soil Quality Index (SQI) decreases with soil depth. Compared to MG, the EF treatment increased topsoil SQI by 38.89–65.71% in the first and second years of restoration, respectively. Comparative evaluation indicated that EF led to more significant increases in vegetation community characteristics than MG. Thus, the EF treatment can significantly enhance the ecological benefits of typical degraded grasslands.

Biogas slurry is rich in nitrogen, phosphorus and bioactive substances, making it an effective material for restoring degraded grasslands. Against this background, we conducted a field experiment in Zhenglan Banner, Xilingol League, Inner Mongolia Autonomous Region, China, from 2024 to 2025, to study the short-term effects of biogas slurry fertilizer on vegetation characteristics and above- and belowground plant traits. The experiment comprised three treatments: a water control (CK), 50% diluted biogas slurry (BS_50%), and full-strength biogas slurry (BS_100%). All treatments were applied at a rate of 300 m³·ha⁻¹, with CK receiving an equivalent volume of water. The biogas slurry contained 0.11% nitrogen (N), 0.07% phosphorus (P₂O₅), and 0.09% potassium (K₂O). Results showed that, compared with the control, biogas slurry application increased plant height, coverage, and biomass by 8.04–54.00%, 5.48–17.76%, and 18.40–96.01% in the first year, respectively. Plant crude protein and crude fat also increased by 7.33–31.17% and 21.54–30.00%. In the second year, the increases were 26.41–50.22%, 6.16–20.55%, and 13.91–52.42% for plant height, coverage, and biomass and 4.46–28.27% and 14.24–19.89% for crude protein and crude fat, respectively. The carbon, nitrogen and isotope indices of leaves and roots also increased simultaneously. Biogas slurry application altered plant community composition, BS_50% transiently increased plant family richness, BS_100% exerted persistent inhibitory effects, and species diversity across all fertilization treatments showed a recovery trend in the second year. Principal component analysis and redundancy analysis showed that treatment groups were clearly separated in 2024 but overlapped substantially in 2025. Root δ¹³C and root δ¹⁵N were key indicators distinguishing vegetation community characteristics. The results of this study confirmed that the application of biogas slurry fertilizer could actively improve the vegetation recovery of degraded grasslands. It provided reference support for the resource utilization of biogas slurry fertilizer and the sustainable management of grassland ecosystems.

The authors would like to make the following corrections to the published paper