中文摘要：

在农田愿望在土壤的地区性的特征上学习器官的碳(SOC ) 密度不仅极大地作出贡献到土壤生产力改进的技术，而且给在土壤为碳隐遁做的技术选择和政策的证据。基于中国的第二国家土壤甸，在农田的犁层的 SOC 密度的状况在不同土地利用模式下面被分析。结果证明在犁层的那 SOC 密度是在从 0.81 ～ 12.68 kg m-2 的平均变化的大约 3.15 kg m-2。最高的密度与 3.63 kg m-2 的一般水准在东南的区域被发现，当时与 3.00 kg m-2 的一般水准的在西北的区域的最低发生。在农田的犁层的 SOC 密度的变化系数是 57% ，它是 35% 比非农田土壤的低。在干燥陆地把密度比作 SOC，在水稻土的 SOC 密度与在不同区域之间的一个更低的变化系数更高是 13% 。另外，在气候因子(累年平均温度和降水) 之间的关系和 SOC 密度比在非农田土壤的那些在农田是更低的，以及在农田的干燥土地比那些在水稻土降低。这些结果建议人为的骚乱在农田土壤在 SOC 密度上有大影响，特别在水稻土，显示收割的中国大米可以极大地作出贡献到在稻田的 SOC 稳定性和隐遁。

英文摘要：

Study on the regional characteristics of soil organic carbon （SOC） density in farmland will not only contribute greatly to the technique of soil productivity enhancement, but also give evidences of technique selection and policy making for carbon sequestration in soils. Based on the second national soil survey of China, the situation of SOC density in the plow layer of farmland was analyzed under different land use patterns. Results showed that SOC density in the plow layer was about 3.15 kg m^-2 in average ranging from 0.81 to 12.68 kg m^-2. The highest density was found in the southeastern region with an average of 3.63 kg ma, while the lowest occurring in the northwestern region with an average of 3.00 kg m^-2. The variation coefficient of SOC density in the plow layer of farmland was 57%, which was 35% lower than that of non-farmland soils. Compared to SOC density in the dry land, SOC density in paddy soils was 13% higher with a lower variation coefficient between different regions. In addition, the relationships between the climatic factors （annual average temperature and precipitation） and SOC density were lower in farmland than those in non-farmland soils, as well as lower in paddy soils than those in dry land of farmland. These results suggest that anthropogenic disturbances have great impacts on SOC density in farmland soils, especially in paddy soils, indicating that Chinese rice cropping may contribute greatly to the SOC stability and sequestration in paddy field.