Effects of biochar-based phosphate fertilizer and supplementary seeding on soil respiration in desert steppe

More than 90% of grasslands in the country have been degraded to varying degrees. Restoring degraded grasslands is an important way of increasing grassland carbon storage under the current dual carbon background. It is highly important to explore the impact of different grassland restoration measures on soil carbon emissions. Therefore, this study set up four treatments in the desert steppe sample of Siziwang Banner, Inner Mongolia including the control (CK), biochar-based phosphate fertilizer (CB), supplementary seeding (CP), and biochar-based phosphate fertilizer with supplementary seeding (CPB). The soil respiration rate was measured, and the soil physical properties (soil temperature and water content) and soil chemical properties (soil organic carbon and available phosphorus) were measured at 0－20 cm. Meanwhile, the vegetation aboveground biomass was investigated during the growing season in June－October of 2021. The results have shown that, compared with the control, the soil water content and soil respiration rate increased by 12%, 15% and 27%, 30%, respectively. The soil temperature decreased by 2.5% and 4.6% under the CP and CPB treatments. The CB treatment improved the soil chemical properties but had no effect on soil respiration. This study has shown that replanting and fertilization + reseeding measures can promote soil respiration over relatively short timescales. Considering the changes in vegetation and soil, biochar-based phosphate fertilizers can promote the restoration of desert grasslands. However, with fertilizing and reseeding measures, attention should be paid to controlling the size of the trenches in the early stages to minimize soil disturbance.