黑土坡耕地侵蚀和沉积对物理性组分有机碳积累与损耗的影响  

EFFECTS OF SOIL EROSION AND DEPOSITION ON LOSS AND ACCUMULATION OF SOIL ORGANIC CARBON IN PHYSICAL FRACTIONS

作　　者：方华军[1] 杨学明[2] 张晓平[2] 梁爱珍[2] 申艳[2] 

机构地区：[1]中国科学院地理科学与资源研究所,北京100101 [2]中国科学院东北地理与农业生态研究所

出　　处：《土壤学报》2007年第3期467-474,共8页Acta Pedologica Sinica

基　　金：中国科学院国外杰出人才支持项目(K09Z3);国家自然科学基金项目(40601097和40471125)资助

摘　　要：以侵蚀和沉积过程明显的黑土坡耕地为研究对象,通过测定不同地形部位表层和典型剖面土壤不同粒级的水稳性团聚体、颗粒态有机碳(POC)以及团聚体结合态有机碳含量,探讨土壤侵蚀和沉积对土壤有机碳(SOC)损失、迁移和累积过程的影响。研究结果表明:上坡三个侵蚀部位表层土壤大团聚体、矿质结合态有机碳(MOC)以及团聚体结合态有机碳含量随侵蚀速率增加而减小;沉积部位(尤其是坡脚)POC含量和POC/SOC较低,而MOC含量和MOC/SOC较高。始终处于沉积状态的坡脚部位,各粒级有机碳组分的深度分布均表现出土壤累积和埋藏特征,并随着粒级的减小累积现象趋于明显。上述结果反映了土壤侵蚀优先使与细颗粒和微团聚体结合的SOC迁移流失,并在低洼的沉积区累积;埋藏层中的侵蚀物质(如微团聚体、颗粒态有机质)通过深埋作用和重新团聚作用形成稳定的大团聚体,最终促进SOC的固定。A typical undulating tract of farmland in the Black Soil region of Northeast China was taken for a case study to analyze impact of soil erosion and deposition on loss, transportation and accumulation of SOC through measuring contents of water stable aggregates of different sizes, particulate organic carbon and aggregate-bound organic carbon in surface layers and typical soil profiles in different topographic positions. Results show that water stable macro-aggregate, mineral-bound organic carbon （MOC） and aggregate-bound organic carbon decreased in content with increasing rate of soil erosion at three sampling sites on the upper slope, and the contents of particulate organic carbon （POC） and POC/SOC ratios were lower at the deposition sites, especially in foot-slope, at the erosion sites, while the contents of MOC and MOC/SOC ratios displayed a reverse trend. The depth distribution of organic carbon of various particle-size fractions at the foot-slope was characterized by obvious accumulation and deep burying of eroded materials; and accumulation was getting more and more obvious with decrease in particle size of the organic fraction. The above-listed findings reflect that soil erosion tends to transport organic carbon associated with fine particles and micro-aggregate, and then accumulates in depressed deposition sites. The eroded materials, such as micro-aggregates, particulate organic matter （POM） in the buried layer form stable macro-aggregates through deep burying, which eventually promotes sequestration of SOC in the deposition sites.

关 键 词：土壤侵蚀 水稳性团聚体 颗粒态有机碳 团聚体结合态有机碳 黑土 

分 类 号：S153[农业科学—土壤学]