Mineralization of soil organic carbon and its relations with soil physical and chemical properties on the Loess Plateau
黄土高原土壤有机碳矿化及其与土壤理化性质的关系

Soil organic carbon (SOC) mineralization is closely related with carbon cycle in terrestrial ecosystem and global climate change. In this research, SOC mineralization and physicochemical properties of 98 soil samples with 7 typical soil types on Loess Plateau were measured after incubation, and the relationship between the two items were analyzed. The results showed that daily amounts of SOC mineralization at early incubation period were greater than that of late period, i.e., mineralization rate decreased gradually. SOC mineralization was observed closely related with soil types, as differences of averaged daily amount, accumulative amount and rate of SOC mineralization among different soil types were significant. Among the 7 soil types, highest accumulative amount of CO2-C was found released from cinnamon soil, about 0.252 g?kg-1, the lowest was aeolian sandy soil, only 0.095 g?kg-1. The accumulative amount of SOC mineralization of subsoil was lower than that of upper layer, but no obvious effect of soil depth was found. The dynamics of SOC mineralization preferably followed the first-order kinetics. Both Cp and k values of all soils were low, Cp ranged from 0.329 to 0.116 g?kg-1 and k ranged from 4.55 to 8.57×10-5 d-1. Soil types had great influence on Cp values, no obvious effects on k values and Cp/SOC ratio were found. Index Cp was found positive and very significantly correlated with SOC, TN, TP, available K, clay content and silt content, while the correlations of Cp with k constant, pH and sand content were significant negative. Our case may provide some references for the research of soil organic carbon pool and cycling on Loess Plateau.