农田和果园土壤有机碳氧化稳定性和储量差异

不同土地利用方式下有机碳的含量和性质变化越来越受到人们的关注。以黄土高原南部高原沟壑区(长武地区)塬面上农田以及不同树龄的果园为对象,研究了土壤总有机碳、易氧化有机碳和难氧化有机碳含量,比较了不同利用方式下土壤有机碳的氧化稳定系数(Kos)和有机碳密度差异。结果显示,该区域果园表层土壤总有机碳的整体水平与农田相当,但果园总有机碳、易氧化有机碳随果园年限增长有降低的趋势。在土壤剖面中,总有机碳、易氧化有机碳及难氧化有机碳都随深度下降而下降的趋势;而Kos值随剖面深度和果园年限增长而呈升高的趋势。0～2 m土壤剖面有机碳储量从高到底顺序是:农田>新果园(小于5年果园)>盛果期果园(10～15年果园)>老果园(15年以上果园)。以农田为基准,在0～200 cm厚度土层中,新果园有机碳储量下降了6.1%,盛果期果园下降了9.3%,老果园有机碳储量下降了22.4%。说明随着果园年限的增长,土壤有机碳储量降低。

The Difference of the Storage and Oxidation Stability of Soil Organic Carbon in the Soil Between Farmland and Orchards

The amount and properties of organic carbon under different land use types are popular concerned.With the different landuses of the farmland and orchards in southern region of loess plateau,the total soil organic carbon,readily oxidized and difficultly oxidized organic carbon were studied,and the oxidation stability and storage of soil organic carbon were calculated and compared.The results showed that although the content of total organic carbon in all orchards soil including new,fully bearing and old orchards was almost in the same level with that of the farmland soil,total organic carbon and easily oxidized organic carbon decreased with the aging of orchards.In the soil profile,total organic carbon,easily oxidized and difficultly oxidized organic carbon decreased with soil depth and orchards age,but the changes of Kos value were on the contrary.The order of soil organic carbon storage from 0 to 200 cm is farmland> new orchard(less than 5 years) > Full bearing period orchard(10-15 years) >old orchard(above 15 years).Compared to the farmland,the storages of soil organic carbon in different soil profiles from 0 to 200cm were decreased by 6.1,9.3 and 22.4% in new orchards,fully bearing orchards and old orchards,respectively.This indicated that the storage of soil organic carbon reduced with the orchard age increase.