长期耕种土壤剖面累积有机碳量的空间分布及影响因素

以陕西关中地区古老的耕种土壤——填土（系统分类属土垫旱耕人为土）为对象，研究了长期耕种及施肥对土壤剖面有机碳贮量及分布的影响。结果表明，供试的7个土壤剖面由于人为生产活动形成的覆盖层的厚度在40-71cm之间（平均59cm），其中有机碳贮量平均达59268kg·hm^-2，占0-100cm土壤剖面有机碳贮量的69％。与同一区域由黄土母质新垦殖的土壤相比，长期耕种填土剖面有机碳的贮量显著增加；为期7a的定位试验也发现，施用有机肥显著提高了0-100cm土壤剖面有机碳贮量，说明长期耕种及施用有机肥在增加土壤剖面有机碳贮量方面具有突出的效应，几千年的农业生产显著增加了土壤有机碳贮量。在全球气候变暖的情况下，填土这一古老的农业土壤为实现农业生产与环境保护“双赢”的目的，为进一步研究这类土壤有机碳累积及稳定性的机理，以及大量施用化肥特别是氮肥对土壤剖面不同层次累积有机碳的转化的影响等问题，提供了理想的研究材料。

Stock and Distribution of Organic Carbon in the Profiles of Soil with Long Cultivating History

The Lou soil （Typ -Eum -Orthic Anthrosols） located at Guanzhong plain, Shaanxi Province, was sampled to investigate the effects of cultivation and fertilization on the stock and distribution of organic carbon in the soil profiles. Results showed that the depths of anthropogenic layer of 7 soil profiles were in range of 40 to 71 cm（ averaging 59 cm ）; and organic C stocks in this layer was 59 268 kg·hm^-2, accounting for 69% of organic C stocks in 0-100 cm soil profiles. Organic C stocks in Lou soil was higher than that in the newly cultivated soil developed from loess parent materials. 7-year fertilization field experiment indicated that the application of organic fertilizer significantly increased the organic C stocks in 0-100 cm soil profiles. It indicated that long-term cultivation and manuring had positive roles in increasing organic C stocks in soil profile. It is needed to study the mechanism of the accumulation and stabilization of organic C in the soil to balance agricultural production and C sequestration.