黄土区煤矿排土场重建草地土壤剖面有机碳变化特征

Soil Organic Carbon Profile Distribution of Rehabilitated Grasslands on the Opencast Coal Mine Dump of Loess Area

以黄土区露天煤矿排土场的4种人工草地和自然恢复的撂荒草地为主要研究对象,研究了草地重建对排土场重构土壤有机碳含量和分布的影响。结果表明:人工草地显著提高了表层土壤有机碳含量,0~10 cm土层有机碳含量达到了4.95 g·kg^(-1),撂荒草地对各土层有机碳含量都没有显著提高;4种人工草地土壤有机碳含量剖面分布为:在0~10 cm土层为苜蓿(Medicago sativa)>沙打旺(Astragalus adsurgens)>甘草(Glycyrrhiza uralensis)>冰草(Agropyron cristatum),在10~100 cm各土层为甘草>冰草>苜蓿>沙打旺;排土场人工草地土壤有机碳含量随土层深度的增加而降低,0~10 cm到10~20 cm降低幅度最大,20~100 cm土层之间降低幅度较小无显著差异;排土场人工草地0~100 cm土层SOCD平均值为3.02kg·m^(-2),是撂荒草地的1.72倍,新建排土场的1.99倍,达到了小流域退耕草地的79%,原地貌草地的62%。草地重建影响排土场土壤有机碳剖面分布,显著提高了表层土壤有机碳储量所占比例,苜蓿和沙打旺较大程度的提高了表层土壤有机碳含量,冰草和甘草对0~100 cm各土层有机碳含量均有一定的提高。

Soil organic carbon（SOC） contents and distributions of rehabilitated grasslands of four different types and abandoned grassland on the opencast coal mine dump of loess area were analyzed.Results showed that SOC content was significant increase at the topsoil of rehabilitated grassland reaching 4.95g·kg^（-1）,and no significant increase at all tested soil layers of abandoned grassland.In the 0～10 cm soil layer,the SOC contents of rehabilitated grasslands were ordered as Medicago sativa〉Astragalus adsurgens〉Glycyrrhiza uralensis〉Agropyron cristatum;while in the 10～100 cm soil layer,the order was Glycyrrhiza uralensis〉Agropyron cristatum〉Medicago sativa〉Astragalus adsurgens.Content of SOC decreased generally with the increase of soil depth,and had sharp reduction from 0～20 cm to 20～40 cm,whereas there was no significant reduction in 20～100 cm soil layers.The value of soil organic carbon density（SOCD） in the 0～100 cm soil depth of rehabilitated grassland was 3.02 kg·m^（-2）,1.72 times higher than abandoned grassland and 1.99 times than new dump,79%of rehabilitated grassland in small watershed and 62%of natural grassland in original landform area.Rehabilitation of grassland changed the SOC profile distribution of the dump and increased the percentage of SOCD in topsoil significantly.Medicago sativa and Astragalus adsurgen could increase the SOC content of topsoil greatly;while Glycyrrhiza uralensis and Agropyron cristatum increased the SOC contents of all tested soil layers.