黄土高原土壤有机碳矿化及其与土壤理化性质的关系

土壤有机碳矿化与陆地生态系统碳循环和全球气候变化密切相关。采集98个共7类黄土高原土样,通过密闭培养法对有机碳矿化动态进行分析,探讨了土壤理化性质对有机碳矿化的影响。结果表明,黄土高原地区主要土壤有机碳在培养初期日均矿化量较高,之后逐渐降低。土壤类型对黄土高原土壤有机碳矿化影响较大,不同土壤有机碳的日均矿化量、累积矿化量和矿化率具有显著或极显著的差异。褐土有机碳总矿化量最高,CO2-C达到0.252g.kg-1,风沙土最低,CO2-C仅为0.095g.kg-1。下层土壤的有机碳矿化量较上层的有所下降,但土层深度对有机碳矿化大体上无明显影响。一级动力学方程能很好模拟黄土高原土壤有机碳矿化特征。供试土壤有机碳矿化潜力(Cp)和矿化速率常数(k)值均较低,分别为0.329-0.116g.kg-1和4.55-8.57×10-5d-1。不同土壤的Cp值变异较大,而k和Cp/SOC值无明显的变异。土壤Cp与土壤总有机碳、全氮、全磷、速效钾、粘粒和粉粒含量均呈极显著的正相关,而与k、pH值和砂粒含量呈显著的负相关。研究结果对黄土高原土壤有机碳循环和土壤碳库研究具有重要的科学价值。

Mineralization of soil organic carbon and its relations with soil physical and chemical properties on the Loess Plateau

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.