Study On The Changes Of Soil Organic Carbon Content And Greenhouse Gas Emissions Law In Jilin Qianguo Saline-alkaline Paddy Field Soil

Soil carbon pool is the most active carbon pool on the surface of the earth whosedynamic changes directly affect the concentration of greenhouse gases in theatmosphere. Since the problem of global warming is getting worse, many countrieshave attempted to seek ways to reduce the emissions of greenhouse gases such as N₂Oand CH₄. The research of paddy fields has become one of hot issues of global changeresearch because paddy fields have a wide range of distribution, a huge area and ahigher carbon-sink capacity. Studies have shown that by the means of reasonable fieldmanagements, proper irrigation systems and optimized fertilizations, the farmland soilcarbon reserves can be increased while the greenhouse gas emissions become lower.Qianguo in JilinProvince, the country’s major grain production base, which has aspecial geographical location and typical paddy fields development characteristics,has been chosen the study area of this paper. Since land development and regulationproject was taken in2007in Qianguo, the area paddy fields increased a lot. The studywas supported by my tutor’s National Natural Science Foundation Project——Soilorganic carbon change mechanism and warming potential research of saline-alkalipaddy soils throughout the year in JilinProvince. Combining field samplings and cellexperiments to study the variation of paddy fields SOC and the carbon storage ofpaddy fields, the emissions law of CH₄and N₂O during rice growth period of paddyfields with different development year has been explored. We also comprehensivelyanalyzed the influencing factors with the actual situation and proposed optimizedwater and fertilizer management measures of paddy fields.Firstly, collecting six paddy field soil samples of different development year （0a,6a,15a,22a,37a and57a） using space scales instead of time scales, testing theorganic carbon content with potassium dichromate-concentrated sulfuric acidmethod. Based on the analysis, we have made comparative analysis of the timechanges and the longitudinal changes of the SOC. The results showed that: SOC content and SOCD of paddy fields increased with the increase of the developmentyears, the longitudinal distribution of the SOC show a decreasing trend from the toplayer to the under layer. Furthermore, the increasing rate of the SOC reducedgradually with the increase of the development years, SOC content in paddy fieldsgradually stabilized after30a. Compared with other land types, the average organiccarbon content of the paddy fields tends to be much higher.Secondly, N₂O emissions of paddy field of different development years duringgrowing season has four peaks: mid-June, early July, early August and earlySeptember, the first three peaks appeared after fertilization, the emergence of last peakwas the result of drainage operations in early September and the peak seemed to beless than others. PH and soil SOC have little effect on N₂O emissions and show littlerelations, but strongly influenced on the application of fertilizers and field moisturechanges, after fertilization and drainage the N₂O emissions of paddy fields creased alot.Again, CH₄emissions of paddy fields with different development years show asingle peak in mid-July, the higher emissions level of CH₄can last about30dayscompared to other time. Many complex factors that affect the CH₄emission, such aspH value, SOC, temperature, moisture and soil organic carbon content to some extent.There are some particularities of CH₄emissions for its special soil environment inQianguo saline-alkali paddy soil, newly-developed paddy fields have higher PH valuethat makes CH₄emissions a lower level, in addition higher temperature, suitablemoisture conditions leads to increasing CH₄emissions, CH₄emissions show asignificantly increasing trend with different development years of paddy fields.The study aimed at paddy field soil organic carbon change and greenhouse gasemissions of Jilin Qianguo, has very strong pertinence,which adopt a variety ofresearch methods including interpretation of remote sensing, field measurements andplot experiment test to monitor greenhouse gas emissions of paddy fields in therice-growing season and to assess paddy field soil carbon sequestration potential ofQianguo. Multi-angle studies in the paddy field soil carbon pools have some newideas and have an important meaning whether in the technical aspects of rich paddy carbon dynamics research, or theoretical level of the exploration of the carbon cyclein the regional scale, as well as the actual production level of assessment andguidance for the development of low-carbon agriculture.