汉中盆地秸秆还田撂荒和林地对土壤碳的影响

农业活动是温室气体重要的排放源,土壤碳库土壤有机碳(SOC)和无机碳(SIC)]稍微变化会对大气CO_2产生很大影响。汉中盆地是南水北调的重要水源涵养地,在该区域秸秆还田、农田撂荒和林地是目前常见土地利用方式,但缺乏不同利用方式对SIC和SOC影响的研究。该研究采集该区域典型样地土壤,用滴定法和有机碳分析仪分别测定其SIC和SOC含量,研究3种土地利用方式对土壤碳库的影响。结果表明:SOC随土层深度最为敏感的是农田,其次是撂荒地,林地最不敏感。0~140 cm土层SOC碳密度,林地最大,是撂荒田的2.26倍,农田是撂荒田的1.37倍。深土层SOC碳密度,林地是撂荒田的2.44倍,农田是撂荒田的1.07倍。撂荒田的SIC密度最大,其次是农田,林地的SIC碳密度最低。在0~140 cm土层中,SIC密度依次为12.37、11.68和9.77 kg·m~2,撂荒田的SIC碳密度是林地的1.27倍。随着我国农村发展,土地利用管理出现新的方式,今后在估算土地利用管理方式对土壤碳影响时还需要综合考虑SOC和SIC。

Effects of straw returning farmland, abandoned land and woodland on soil carbon in Hanzhong basin

Due to the increase of atmospheric gas concentration in greenhouse, climate warming caused great inconvenience to people''s production and living. Therefore, soil carbon pool soil organic carbon(SOC)and soil inorganic carbon(SIC)] has attracted much attention. Straw returning farmlands and abandoned farmland changed the input carbon, which affected the SIC and SOC conversion processes and soil carbon pool. SIC has a long retention time, and SOC plays an important role in the formation of soil aggregates and the adsorption of mineral nutrients for plants. With rural population reduction, straw returning farmland, abandoned land and woodland are very common. There is lack of research on the effects of land use change on different soil carbons. The results showed that SOC is the most sensitive to the soil depth of the farmland, followed by abandoned land, the lowest sensitive forest land. The density of SOC in the topsoil of forest land was the largest, followed by farmland, and the smallest was abandoned. The SOC carbon density in woodland was 2.26 times of that in abandoned land. SOC carbon density in farmland was 1.37 times of that in abandoned land in 0-140 cm soil. The abandonment farmland SIC density was the biggest, followed by farmland, with the lowest SIC carbon density in forestlands. In the 0-140 cm soil layer, the SIC densities were 12.37, 11.68 and 9.77 kg · m^-2, respectively. SIC carbon density in abandoned fields was 1.27 times that of woodland. With the development of rural areas in China, a new way of land use management has emerged, estimating the impact of land use on soil carbon needs to consider SOC and SIC.