农业利用方式对土壤有机碳库大小及周转的影响研究

Effects of Agricultural Land Use Types on Soil Organic Carbon Pool Size and Turnover

通过土壤样品的室内培养,运用三库一级动力学理论,以丘陵区红壤为对象,研究了水田、桔园、旱地、水旱轮作4种土地利用方式农田土壤有机碳库大小、各碳库平均周转时间及分解动态,探讨了土地利用变化对土壤有机碳的影响。结果表明,土壤有机碳分快速分解和缓慢分解两个阶段。快速分解阶段的分解速率与活性碳含量和活性碳占有机碳的百分含量相关性不明显;缓慢分解阶段的速率与缓性碳库含量呈正相关。4种土地利用类型表层和中层土壤总有机碳含量分别为4.97～12.40g/kg,2.58～4.00g/kg;缓性碳库表层含量的大小顺序为:水田(5.78g/kg)>旱地(3.77g/kg)>桔园(3.39g/kg)>水旱轮作(2.83g/kg);惰性碳库表层含量的大小顺序与缓性碳相同,含量分别为6.42,5.43,2.45,2.03g/kg,水田的缓、惰性碳库含量最高,水田更具有固碳潜力。

This paper takes the red soil of hilly region as the target which study the paddy land ,citrus orchard,upland,rotation between upland crop and paddy rice that use three carbon pool sizes,average turnover time and the dynamics of soil organic carbon （SOC） decompositions of land use change on the base of first order dynamic model,combining with a laboratory soil incubation experiment. The results showed that soil organic carbon decomposition has two stages： one is rapid decomposition in early time,and the other is slow decomposition in late time. Rapid decomposition has not significant correlation with active carbon pool size and percentage of total soil organic carbon;The rate in slow decomposition period is positively related with the slow carbon pool. The four land use types total soil organic carbon are 4.97-12.40 g/kg in the surface soil and 2.58-4.00 g/kg in the subsoil. The slow carbon pool can be ranks as： paddy land（5.78 g/kg） 〉upland（3.77 g/kg）〉citrus orchard（3.39 g/kg）〉rotation between upland crop and paddy rice（2.83 g/kg）;The ranks of passive carbon pool are the same as slow carbon pools. The content of passive carbon pool is 6.42,5.43,2.45,2.03 g/kg,paddy land is the biggest one in slow and passive SOC pool and it will be a large carbon sink.