The Influence of Freeze-thaw Effect and Moisture Content on Active Organic Carbon in Black Soil
[Objective]Conducting research on the impact of freeze-thaw conditions on soil active organic carbon can provide basic data and theoretical basis for the study of organic carbon conservation and carbon balance in black soil areas.[Method]Taking typical middle layer black soil in Dehui area as the research object,the effects of different freeze-thaw cycles,freezing time,freeze-thaw temperature,and moisture content on soil active organic carbon were investigated through freeze-thaw control experiments.[Result]There were significant differences in the response of soil active organic carbon components to freeze-thaw conditions.The content of Dissolved Organic Carbon(DOC),Light Organic Carbon(LFOC),and Particulate Organic Carbon(POC)in soil gradually increases with the increase of freeze-thaw cycles,and the growth rate slows down after 20 freeze-thaw cycles;Soil Microbial Biomass Carbon(MBC)fluctuates between 0.160 g kg-1 and 0.164 g kg-1 after 12 freeze-thaw cycles.Both a decrease in freezing temperature and an increase in melting temperature can promote an increase in soil DOC,LFOC,and POC content,while the soil MBC content decreases with a decrease in freezing temperature and increases with an increase in melting temperature.However,the content still decreases by 10.42%to 24.48%compared to the control state.The content of soil DOC,LFOC,and POC showed significant differences with the increase of freezing time,with a significant increase from 12 to 48 hours;The increase in freezing time resulted in a significant decrease in soil MBC content,with a decrease of 52.60%at 96 hours of freezing time.As the moisture content increases,the content of soil DOC,LFOC,and POC gradually increases.When the relative moisture content is between 80%and 100%,the increase in LFOC content is most significant,ranging from 9.69%to 38.48%;The soil MBC content gradually decreases,and the decrease tends to be gradual when the relative water content is between 80%and 100%.[Conclusion]The freeze-thaw cycle is beneficial for enhancing or maintaining soil organic carbon,and frequent freeze-thaw cycles can increase the content of some active organic carbon components and promote soil nutrient cycling.
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