宜居山地土壤机械组成对有机碳含量的影响

以位于适合人类居住黄海沿岸的大连市金州区大黑山松树林和玉米田为研究对象，分层采集土样，测定粘棕壤有机碳含量和机械组成。研究不同土地利用方式下土壤机械组成对有机碳含量的影响。结果表明：土壤有机碳含量的空间垂直分布总体上随着土壤深度增加而降低。松树林和玉米田土壤有机碳平均含量分别为7.619g/kg和5.971g/kg。土壤有机碳含量不同层次间差异极显著(P＜0.01)。土壤机械组成与有机碳含量呈现显著的相关关系。松树林土壤粉粒平均含量与有机碳平均含量的相关性最大(R²=0.8822)，玉米田土壤砂粒平均含量与有机碳平均含量的相关性最大(R²=0.9786)；松树林、玉米田土壤粘粒含量与有机碳平均含量的相关性最小（分别为R²=0.8186、0.6145）。粉粒在各层土壤中所占的平均含量(＞32%)最大。松树林土壤的粉粒和玉米田土壤的砂粒含量可以作为有机碳含量的一个预测因子，用来估计土壤有机碳的含量。

The effect of the concentration of clay organic carbon on particle-size composition in the hill region of the suitable inhabitancy

The relations between the concentration of clay organic carbon and soil particle-size were studied in Pine forest and Maize field of different land-uses in the Jinzhou region of Dalian. Soil samples were collected according to profile layers, and soil organic carbon concentration, soil particle-size composition were measured and analyzed statistically. Results showed that vertical distribution of soil organic carbon content varies with soil depth and land use type, and the order of soil organic carbon mean concentrations were: Pine forest (7.619g/kg) > Maize field (5.971g/kg). The relation between the concentration of clay organic carbon and soil particle-size was highly significant (P<0.01). The correlation between the content of pine forest silt and the mean content of soil organic carbon was the biggest (R²=0.8822) so as to that of sand grain of maize field (R²=0.9786), while the correlation between the content of clay and the mean content of soil organic carbon both pine forest and maize field was the least (respectively=0.8186, 0.6145). The percentage of silt content was the highest(＞32%) in each soil layers. And the correlation with the content of silt was higher than that of clay, so the content of silt could be an important index of soil organic carbon so that use it to estimate the concentrations of soil organic carbon.