中亚热带主要农业土壤有机碳及其组分特征

为了解中亚热带主要粮油产区土壤肥力状况,本文通过野外采样和室内测定,对研究区主要农业土壤的有机碳及其组分含量特征展开研究。结果表明:研究区土壤有机碳(SOC)含量在紫色土上含量最高,红壤地区则偏低,肥力水平不高。易氧化有机碳(EOC)与SOC变化趋势一致。轻组有机碳(LFOC)、粗颗粒有机碳(CPOC)、细颗粒有机碳(FPOC)分别在红壤、河潮土、水稻土中比重最大,这与土壤母质及发育年龄有关。不同利用方式下,茶园土壤SOC含量最高,SOC含量变化序列表现为:茶园地>玉米地>水稻-油菜地>棉花地>菜园土。茶园土壤EOC/TOC值为36.85%,表明该土壤SOC的稳定性高。其他农业土壤EOC/SOC值变化不大,在22.48%~25.52%之间,平均值为23.44%。LFOC与CPOC比SOC对土地利用方式的变化更为敏感,受SOC、CEC、NO₃^--N、NH₄⁺-N的影响显著(P<0.01)。

Characteristics of Soil Organic Carbon Fractions of Main Agricultural Soils in Mid-subtropical Areas

In main agricultural regions of mid-subtropical zone, to understand soil fertility status, the authors studied the content and accumulation characteristics of soil organic carbon components by field sampling and indoor analysis. The results showed that: the content of organic carbon (SOC) in purple soil was the highest, while the red soil had low organic matter content and the fertility level was not high. The variation tendency of soil easily oxidized organic carbon (EOC) was consistent with SOC. Light fraction organic carbon (LFOC), coarse particulate organic carbon(CPOC), fine particulate organic carbon(FPOC) had the largest proportion in red soil, river tidal soil and rice soil, respectively, which were related to soil parent material and development age. Under different utilizing ways, the content of SOC in tea garden was the highest. The sequence of SOC was tea garden > corn field > rice-rape field > cotton field > vegetable garden. The value of EOC/SOC in tea garden was 36.85%, which indicated that the soil organic carbon was stable. The value of EOC/SOC of other agricultural soils changed a little, ranging from 22.48% to 25.52%, with an average value of 23.44%. LFOC and CPOC were more sensitive to land use change than SOC, and were significantly affected by SOC, CEC, NO₃^--N and NH₄⁺-N (P<0.01).