基于安徽省霍山县第二次土壤普查数据,提取2005～2008年耕地监测数据资料建成土壤有机碳含量数据库,对耕地监测的有机碳数据按县域内不同空间尺度进行了统计分析。结果表明:20年来该县农田表土有机碳含量明显提高,显示农田土壤的有机碳库积累。县域范围内耕地土壤有机碳含量的不同尺度的变异系数介于4.53%～14.91%。村民组(自然村)单元内变异性最高,有机碳含量乡镇间变异性低于行政村间变异性。因此,从县级尺度的农田土壤碳计量来说,以乡镇尺度采样研究比村级尺度可靠性要高。影响县域内农田土壤有机碳含量与变异的动力因子主要是农业利用和农田基本建设,茶、桑和水稻利用下农田土壤有机碳含量明显较高。

Spatial variabilities of soil organic carbon contents in croplands and the influencing factors have been the fundamental issues on estimating SOC stock and C sequestration potential.In this paper,archived data of the 2nd national soil survey and the soil monitoring of farmlands during 2005-2008 in Huoshan County,Anhui Province were collected to create a SOC distribution database.Statistical analysis of the SOC at different spatial scales within the county was conducted.The results showed that SOC contents in the county's farmlands have increased over the last 20 years,indicating SOC accumulation in the farmlands.The statistical variation coefficient of SOC ranged from 4.53% to 14.91% in terms of the size of spatial scales.Variabilities of village scale were much bigger than those of township scale.Thus it is suggested that soil sampling and statistics of SOC contents at spatial scale of townships should obtain higher reliability of SOC pool data than at village scale in the county.Prominent factors influencing SOC levels included land use types and agricultural managements.Results show that SOC contents in tea garden,mulberry field and rice paddy were high in the study area.