Soil nutrients properties of differently aged pastures of Pennisetum purpureum cv. Guimu-1 in the Karst region

Human disturbance and management approaches contribute significantly to ecological restoration of Karst region. This study is to determine the effects of different planting years of Guimu-1 (Pennisetum purpureum cv. Guimu-1) on aboveground biomass, soil nutrients, and soil microbial biomass carbon by comparing the three pastures sites and corn field (Zea mays, CK) in the Karst region. The results of this study showed that the aboveground biomass of Guimu-1 were significantly different among planting years (P0.05) and was in order as 7-y G 1-y G 5-y G. The soil nitrogen (N), phosphorus (P) and potassium (K) in the soil profiles (0-50 cm) decreased firstly and then increased with the increase of the planting years, indicating that they were the lowest in the 5-y G pasture; The soil organic carbon content in each soil layer (0-50 cm) were the highest in the 7-y G pasture, and it was the lowest in the 5-y G pasture. The soil microbial biomass carbon (MBC) in top soil (0-10 cm) were in the order of 1-y G 5-y G 7-y G, and the MBC in 7-y G pasture increased the 32.37% and 19.18% when compared to 1-y G and 5-y G pasture, respectively. Soil organic carbon, total nitrogen, total phosphorus, total potassium at different soil depths and MBC in the top soil were higher in Guimu-1 pastures than those in the corn field with the corresponding soil layers, and soil available nitrogen, available phosphorus and available showed an opposite trend. This study implied that the Guimu-1 pasture enhanced the soil fertility significantly, and the soil carbon sequestration potential was the best in the 7-y G pasture. The implementation of planting grass for raising livestock possibly can be used as an effective restoration and rehabilitation approach in the Karst region.