Study On Soil Carbon Change And Plant Source Carbon Increase Of Songyuan Saline-Alkali Soil Area In Jilin Province Based On Isotope Technique

Soil carbon pool is the largest carbon pool in terrestrial ecosystems,.Along with the global climate warming,its small changes will cause a huge impact.Soil organic carbon and inorganic carbon are important components of soil carbon pool,but the current research is more limited to organic carbon,less consider the impact of inorganic carbon.China is one of the countries that are most seriously affected by soil salinization.Soil salinization not only endangers the growth and development of crops,but also deteriorates the physical properties of the soil and the salinity of groundwater,large areas of land desolation and the reduction of agricultural land.Simultaneously,isotope techniques can be used to trace the source and sink of matter s very well,and to resolve the composition of an element contained.Through the natural abundance of isotopes of soil carbon with different salinity and alkalinity,and the changes before and after the growing season,the conversion of soil organic carbon and inorganic carbon is the study of soil carbon cycle new technology and new topics.Songyuan city of Jilin Province is located in the northeastern transect of China in the study of global climate change and it is one of the three major saline-alkali lands in the world and an important area for studying the distribution and the global carbon cycle.Based on the National Natural Science Foundation of China,"Study on Soil Organic Carbon-Inorganic Carbon Transfer Fluxes and Transformation Mechanism in Saline-Alkali Soils of Western Jilin Province",we taking the upland field planted with corn and the paddy field planted with rice in the Songyuan city of Jilin as the research object,by systematically testing in order to study the basic physical and chemical properties of soil salinization and soil organic carbon,inorganic carbon content and stable isotopes of organic carbon,inorganic carbon(?¹³C value)to reveal the variation of carbon stable isotopes in soils with different salinities.Investigated the changes of soil organic carbon and inorganic carbon contents in soils with different salinities and layers,and the relationship between soil organic carbon or inorganic carbon with their?¹³C values.Based on analysis the changes of carbon content in different saline soils during the growing season.,calculated the content and proportion of plant added in soil after the growing season.The results show that:the salinity of paddy soil decreases with the increase of development years,while corn land soil has poor improvement relatively.It means that the maize planting could not very effectively reduce the salinity of soil in saline-alkali soil,while the planting of rice could.The content of soil organic carbon in upland and paddy fields decreased with the increase of salinity.And the content of inorganic carbon increased with the increase of salinity.The changes of soil carbon content of two kinds of farmland at maturity are similar with the seedling stage.Compared with the difference of seedling stage,it was found that the soil organic carbon in upland topsoil increased after growing season,but decreased in deeper soil.And with the increase of salinity,the decreased content of soil organic carbon decreased.While the organic carbon of all soil layers increased in the paddy soils,and the content of soil organic carbon increased with the increase of the salinity levels.The soil inorganic carbon contents of both kinds of farmland increased after the growing season.The?¹³C value of surface soil organic carbon in upland soil changed little with the degree of salinity,while the?¹³C value of deep soil organic carbon decreased significantly with the increase of salinity.The?¹³C value of organic carbon in paddy soil decreased with the increase of salinity.The?¹³C value of soil inorganic carbon increased with the increase of salinity in both kinds of farmland.The greater the?¹³C value of soil organic carbon,the smaller the?¹³C value of inorganic carbon.Combined with the measurement of soil organic carbon content and?¹³C value in farmland,with the increase of salinity,the content of soil organic carbon and its?¹³C value showed a decreasing trend.With the increase of soil salinity,the content of inorganic carbon and its?¹³C value of upland and paddy soil increased in seedling stage.Calculating the proportion of the new plant-derived inorganic carbon in total inorganic carbon and content from the seedling to the mature stage.We found that the new plant-derived inorganic carbon accounted for more than 60%,and f_newew decreased with the increase of soil salinity.While the change of f_new in paddy field is opposite to that in upland,which increases with the increase of salinity.As the content of soil inorganic carbon increased with the increase of salinity,the content of inorganic carbon in newly-added plant-derived soils also increased with the increase of salinity.The results provide new ideas for the study of soil carbon cycle including soil inorganic carbon,which fills the gap of soil carbon migration through the natural abundance and change of isotope,which lays the foundation for the study of transformation mechanism of soil organic carbon and inorganic carbon.This article also provides a basic example of a regional small scale for global carbon cycle research.