吉林西部盐碱地区稻田土壤有机碳矿化特征

以吉林西部盐碱地区(前郭灌区)土壤为研究对象,选取不同盐碱程度的4块水田(P1、P2、P3和P4),采用野外实地调研采样与室内模拟试验相结合的方法,分别在培养期的第1,4,7,10,14,21,28,35,70天测定土壤CO_2气体的排放通量,结合土壤基本理化性质,分析盐碱稻田矿化模拟培养过程中CO_2通量的动态变化,研究土壤盐碱化程度对有机碳矿化过程的影响。结果表明:P1、P2、P3为弱碱化土,P4为强碱化土;各样地土壤有机碳(SOC)含量差异显著,并存在表层富集现象,与碱化度(ESP)呈显著负相关关系(r=-0.945);SOC矿化量累积过程与培养时间符合一级动力学模型C_t=C_0(1-e^-kt),各样地土壤在矿化培养初期CO_2释放量较大,释放强度降低较快,矿化速率随时间延长呈缓慢平稳下降,在培养期结束时降至最低。SOC矿化过程受多种因子共同作用,ESP是该过程的主要影响因子。土壤的盐碱化抑制了土壤碳循环的速度,相对于碳源过程而言,对碳汇的影响更大。伴随SOC含量增加,SOC矿化反应强度和矿化反应的完全程度加强,矿化反应累积量增加,反之,随ESP程度增加而减弱。

Characteristics of Organic Carbon Mineralization in Saline-alkali Paddy Field in Western Jilin Province

In order to investigate the effects of saline-alkali on the organic carbon mineralization process, a method integrating field sampling and lab simulating experiment is used. In the study, exploring the saline-alkaline soil in Qianguo Irrigation District in Western Jilin Province, 4 paddy fields with different saline alkali degrees (P1, P2, P3, P4) were chosen as the experimental subjects. The experiment recorded the soil CO₂ emission flux on the 1st, 4th, 7th, 10th, 14th, 21st, 28th, 35th and 70th day of the incubation period. Combining the physical and chemical properties of soil to compare the dynamic changes of CO₂ flux in the progress of paddy field cultivation simulation among the subjects. The results showed that P1, P2 and P3 were weakly alkaline soils and P4 was strongly alkaline soil. The SOC content of each plot was significantly different and there was a surface enrichment, which was significantly negatively correlated with the degree of alkalization (r=-0.945). The accumulation process of SOC mineralization and culture time was consistent with the First order kinetic model C_t=C₀(1-e-^kt).In the initial stage of mineralization, the amount of CO₂ released was large, and the release intensity decreased rapidly. The mineralization rate decreased slowly with time and decreased to the minimum at the end of the culture period. The study interprets that the SOC mineralization process is affected by a variety of factors. In saline alkaline soils, ESP is the main influencing factors of this process. Salinization of soil inhibits the rate of soil C cycle, which has a greater impact on the C sink than the C source process. The intensity of SOC mineralization reaction, the accumulation of mineralization reaction and the completeness of mineralization reaction increase with the increase of SOC content, and decrease with the increase of ESP level.