冻融作用与含水量对黑土中活性有机碳的影响

The Influence of Freeze-thaw Effect and Moisture Content on Active Organic Carbon in Black Soil

【目的】明确冻融条件对土壤活性有机碳影响程度,为黑土区有机碳保持和碳平衡的研究提供基础数据和理论依据。【方法】以德惠地区典型中层黑土为研究对象,通过冻融控制试验,研究不同冻融频次、冻结时间、冻融温度及土壤含水量对土壤活性有机碳的影响。【结果】土壤活性有机碳组分对冻融条件的响应差异显著。土壤可溶性有机碳、轻组有机碳、颗粒有机碳含量随着冻融频次的增加逐渐增加,当冻融20次后,含量变化幅度较小,逐渐趋于稳定;土壤微生物量碳含量在冻融12次后处于0.160~0.164 g kg^(-1)之间波动。冻结温度降低、融化温度升高均可促进土壤可溶性有机碳、轻组有机碳和颗粒有机碳含量增加,而土壤微生物量碳含量则随冻结温度的降低而降低,随融化温度的升高而增加,但含量仍比对照处理低10.42%~24.48%。土壤可溶性有机碳、轻组有机碳和颗粒有机碳含量随着冻结时间的增加差异显著,冻结时间为12~48 h时,增幅较大;冻结时间增加使得土壤微生物量碳含量显著降低,冻结时间为96 h时,降幅可达52.60%。随着土壤含水量增加可溶性有机碳、轻组有机碳和颗粒有机碳含量逐渐增加,当含水量为田间持水量的80%~100%时,轻组有机碳含量增加最显著,增幅达到9.69%~38.48%;而土壤微生物量碳含量则逐渐降低,当含水量为田间持水量的80%~100%时,含量降低不显著。【结论】冻融循环有利于增强或维持土壤有机碳含量,频繁的冻融作用能够提高部分活性有机碳组分含量,促进土壤养分循环。

[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.