黄土丘陵区退耕撂荒对土壤有机碳的积累及其活性的影响

Effect of Land Abandonment on Soil Organic Carbon Sequestration in Loess Hilly Areas

土壤有机碳是陆地生态系统的重要碳库之一,增加土壤中碳的储量对于减缓全球变暖的趋势具有重要意义。通过野外样品采集及室内分析,比较了退耕1年,3年,5年,7年,10年,15年和25年7个不同年限撂荒地的土壤有机碳及其活性的变化。结果表明:耕地撂荒后,表层土壤有机碳及活性有机碳的含量随着退耕年限的增长呈增加趋势;土壤中的腐殖质以胡敏素为主,占总有机碳含量的70%～80%;深度在40cm以上的表土,腐殖酸总量及各组分含量都随着撂荒年限的增长呈递增趋势。说明耕地撂荒后,土壤中有机碳的含量明显增高,对增加土壤中有机碳的储量具有积极的意义;同时植被恢复后也减少了土壤中有机碳的流失。

This paper compared soil organic carbon content and labile organic carbon content of seven different pastures from abandoned field with field soil samples collected and room-analysis. The results showed that soil organic carbon content and labile organic carbon content increased when tillage was abandoned, and the contents of soil organic carbon and labile organic carbon increased with the increasing of years. We also found that soil humus was mainly consisted of humin, accounting for 70%～80%; the contents of humus acid and its composition decreased with depth, and increased with the increasing of years. And it is significant that it increases soil organic carbon and decreases the loss of soil organic carbon, as the tillage was fallowed.