农业开垦对中国土壤有机碳的影响

以中国土种志资料为基础,分析了耕地和非耕地表层土壤有机碳含量的变异性,以及各大区域土壤有机碳含量在耕地和非耕地、水田和旱地之间的差异;同时结合非耕地有机碳含量和耕地面积数据,估算了由于耕地的开垦而导致的土壤表层有机碳贮量的变化。结果表明,耕地土壤有机碳含量的变异性小于非耕地,水田小于旱地;耕地土壤有机碳含量明显低于非耕地土壤,平均减少了51.5%,水田却明显高于旱地;水田和旱地的开垦分别导致土壤表层有机碳贮量减少了0.67,3.63 Pg,共计4.3 Pg。最后还分析了土壤有机碳库减少量的空间分布格局,探讨了东北和华北这两大区域土壤有机碳贮量下降程度最大的原因,是由于黑土、黑钙土、暗棕壤等富含有机碳的草原草甸和湿地土壤大量开垦以及耕作管理措施粗放所致。

Effect of Agricultural Cultivation on Soil Organic Carbon in China

Based on the data from the National Second Soil Survey,this paper analyzed the variation of topsoil organic carbon(SOC) content in cropland and non-cropland,and the difference of SOC content in cropland and non-cropland,paddy fields and upland field among 6 regions.At the same time,the change of topsoil SOC storage led by cultivation was estimated based on the data of SOC content in non-cropland and cropland area.The results indicated that the variation of SOC content in cropland was less than that in non-cropland,and that in paddy field was less than in upland field;secondly,the SOC content in cropland was less than that in non-cropland which decreased 51.5% in average,but that in paddy field was more than in upland field;thirdly,the loss of SOC pool led by the agriculture cultivation was 4.3 Pg,which including the decreasing of paddy field and upland field was 0.67 and 3.63 Pg respectively.At last,this paper analyzed the spatial distribution of the SOC pool loss,and discussed the reason of the most decreasing degree of SOC storage in Northeast and Northern China,which was the much cultivation of soil like black soil,chernozems,and dark brown soil in grassland and wetland,and the irrational agricultural field management.