The Effect of Different Artificial Grasslands on the Soil Organic Carbon Content in A Degraded Land

To evaluate the improving effects of artificial grassland restoration measures on soil organic carbon (SOC), soil with different depths, 0-5 cm and 5-10 cm, was sampled and three components of SOC, i.e., total organic carbon (TOC) content, water soluble organic carbon (WSOC) content, and hot-water extractable organic carbon (HWEOC) content were measured in artificial grasslands of smooth brome (Bromus inermis) and alfalfa (Medicago sativa) synchronously. Based on the comparison of effects on soil organic carbon pool between these two kinds of artificial grassland, the preliminary conclusions are obtained as follows. Firstly, both artificial grasslands of smooth brome and alfalfa can considerably increase soil TOC for topsoil (0-10 cm) on annual time scale; meanwhile, the monthly fluctuation of TOC for topsoil was violent throughout the year, which may be driven by both phenology of plant species and variation of elemental factors. Moreover, on one-year scale, the TOC of topsoil in alfalfa grassland was higher than that in smooth brome grassland, while WSOC at 0-5 cm soil depth were significantly higher than that at 5-10 cm soil depth, and HWEOC exhibited no difference between the two soil depths. Finally, for the improving effect on all components of SOC, alfalfa grassland performed slightly better than smooth brome grassland, but the difference was not significant, and long-term monitoring is needed.