Effects of exogenous carbon input on soil organic carbon mineralization and temperature sensitivity of cropland and wetland in the North China Plain

The influences of exogenous carbon input and climate warming are two key factors of soil organic carbon mineralization. Based on a ¹³C stable isotope labelling technique, we conducted a laboratory incubation experiment to investigate the priming effect and temperature sensitivity of soil organic carbon mineralization of cropland and wetland in the North China Plain to understand and forecast soil carbon dynamics under global climatic change. Topsoil collected from cropland and wetland of Hengshui region were with or without ¹³C-labeled glucose0.4 mg(C)∙g^-1 at two temperature (15℃ and 25℃) for 35 days. Soil CO₂ emission and its ¹³C isotopic composition was measured at days 1, 3, 5, 7, 10, 14, 21, 28 and 35. Our results suggested that the soil organic carbon mineralization was significantly influenced by land use type, temperature, and glucose addition. The soil organic carbon mineralization of the cropland was approximately equal to that of the wetland without glucose addition but it was significantly higher than that of wetland with glucose addition at the same temperature. Except the wetland soil cultured at 15℃, glucose addition exerted a significantly positive priming effect on soil organic carbon mineralization in wetland and cropland soil. However, the priming effect of the cropland was significantly higher than that of wetland. Soil organic carbon mineralization was also accelerated by increased temperature, and the Q₁₀ value of its temperature sensitivity fluctuated between 1.2 and 1.6 during incubation. The temperature sensitivities of soil organic carbon mineralization were not significantly changed by different land use types and glucose addition. In conclusion, the soil organic carbon mineralization of the cropland was significantly higher than that of wetland under warming conditions and exogenous carbon input.