Effect of nitrogen deposition on Soil CO2 emission during freezing-thawing incubation period

Due to the traditional analysis method on the influence of soil nitrogen deposition on soil emissions during the freezing and thawing period, the initial impact of nitrogen deposition on soil emissions during the freezing and thawing incubation period was not analyzed, resulting in insufficient accuracy of the later analysis results. A new method was proposed to analyze the effect of nitrogen deposition on Soil emission during freeze-thaw cultivation.On this basis, the contents of soil temperature, moisture, inorganic nitrogen and soluble carbon were determined. Three freeze-thaw models of nitrogen deposition levels were established. The influence of nitrogen deposition on Soil emission and the effect of nitrogen deposition on emission in alpine wetland were studied by multivariate variance analysis. The effect of nitrogen deposition on emission of alpine wetland was studied. The results showed that different soil temperature and moisture content had great influence on the seasonal variation of soil flux, which was generally consistent with the single peak of soil temperature, but highly consistent with the variation of soil moisture content in different growth periods. Nitrogen treatment changed the DOC content of soil organic matter. DOC content in mineral layer and organic layer increased significantly in low and medium nitrogen treatments. The emission of soil in freezing period is lower than that in normal temperature period, and that in multiple freezing period is less than that in one freezing period. The emission rate of soil under freeze-thaw condition is the smallest, and the emission rate of soil after thaw is the largest. Appropriate nitrogen deposition can promote soil emission, while high nitrogen deposition can inhibit emission.