松辽平原黑土有机碳含量时空分异规律

松辽平原典型黑土分布区土壤有机碳的空间分异规律及不同开垦年限土壤有机碳含量变化的研究结果表明：随着纬度的增加，黑土总有机碳平均含量由11．43g／k增加至20．83g／kg，有机碳组分含量和HA／FA比值均表现出增加的趋势。随着土壤剖面加深，黑土总有机碳及其组分含量均呈下降的趋势，土壤中的HA—C逐步被FA-C和HU-C所替代。土壤开垦前50年，黑土总有机碳及其组分含量下降迅速，以后下降趋于缓慢，至开垦130年后，有机碳含量水平基本处于相对稳定状态，变化不明显。

Temporal-Spatial Variation Law of Organic Carbon Content in Typical Black Soil on Songliao Plain

The spatial variation law of soil organic carbon(SOC) and the content variation of SOC in different tillage periods in typical black soil distribution area of China were studied. The results show that, with the increase of latitude, the average total black soil organic carbon content increases from 11.43 g/kg to 20.83 g/kg, the organic carbon compositions content and HA/FA ratio show a increased trend. With soil profile depth increased, the black soil total organic carbon and HA-C, FA-C, HU-C contents are decreased, the black soil total organic carbon contents in A , AB and C layers are 16.04-40.28 g/kg , 8.04-13.82 g/kg, 4.84-9.13 g/kg, respectively. The ratio changes of FA-C/SOC, HA-C/SOC and HU-C/SOC are different in soil profiles from A to B layer, the ratio of HA-C/SOC is to reduce gradually with soil profile depth increased, and the ratios of FA-C/SOC and HU-C/SOC are to increase gradually with soil profile depth increased, HA-C is substituted for FA-C and HU-C gradually. It is shown that ability of humus wholly decayed is to reduce with soil profile depth change. Black soil total organic carbon and its compositions content decrease rapidly before 50 years tillage, then decrease slowly. After 130 years tillage, the soil organic carbon content is relative stable basically.