农田土壤有机碳库大小及周转

Pool sizes and turnover rates of farmland soil organic carbon.

对水稻土、早地潮土和红壤下土壤有机碳库的大小、分解速率和平均驻留时间进行了分析,根据有机碳周转时间的不同,可将土壤有机碳库划分为活性碳库、缓效性碳库和惰效性碳库3个库,其遵循三库一级动力学方程,根据土壤有机碳的分解变化,用此方程在SAS8.2软件上拟合出活性碳库、缓效性碳库的大小及其分解速率.结果表明,农田土壤各剖面的活性碳一般占土壤有机碳的0.6%～3.7%,平均驻留时间为4～45 d;缓效性碳库一般占土壤有机碳的37.7%～81.2%,平均驻留时间为5～24年;利用酸水解测得的惰效性碳一般占土壤有机碳的17.1%～48.1%.不同水型及不同母质下的水稻土中各碳库变化规律分别为：潴育型水稻土＞潜育型水稻土＞淹育型水稻土、第四纪红粘土＞第三纪红砂岩类.不同水稻土和旱地土壤中,活性碳库变化规律为水稻土＞旱地,而缓效性碳为旱地土壤＞水稻土,表明旱地土壤的固碳能力较水田强.

This paper studied the pool sizes and turnover rates of organic carbon in paddy soil, upland fluvo-aquic soil and red soil in Yujiang County. According to the turnover time of soil organic carbon, the carbon pools could be clssified into active, slow-active, and inert pools, all of which complied with first order dynamic model. Based on the decomposition curves of soil organic carbon and employing this model, the sizes and decomposition rates of active and slow active carbon pools were simulated, and the results showed that the size of active pool in different soil profiles accounted for 0.6 % - 3.7 % of total soil organic carbon, with a mean residence time of 4 - 45 days, while the size and mean residence time of slow-active pool were 37.7% -81.2% and 5-24 years, respectively. As for inert pool, its size measured by using acid hydrolysis method accounted for 17.1% - 48. 1%. The carbon pool size of paddy soils with different moisture regime was in order of periodically water logged paddy soil〉 glayed paddy soil〉 submerged paddy soil, while that of paddy soils with different parent material was in order of Quaternary red clay 〉 Tertiary red sandstone. Paddy soils had a larger active carbon pool than upland soils, which was reverse in slow-active carbon Pool suggesting that upland soil had a greater ability to fix carbon than paddy soil.