秸秆、木质素及其生物炭对潮土CO_2释放及有机碳含量的影响

Carbon Dioxide Emissions and Organic Carbon Contents of Fluvo-aquic Soil as Influenced by Straw and Lignin and Their Biochars

研究添加秸秆、木质素及其生物炭后潮土CO2释放特征及土壤有机碳含量变化,为合理利用有机物料提供科学依据。采用室内模拟试验,等碳量(1%秸秆/土壤质量比)施入4种物料(秸秆、木质素及其裂解的两种生物炭),分析不同处理土壤CO2释放速率、累积释放量和有机碳、水溶性有机碳(DOC)、易氧化有机碳(ROC)及微生物量碳(MBC)含量的变化与相关性。结果发现,土壤中添加不同物料对土壤CO2释放和有机碳含量有显著影响,秸秆和木质素能提高土壤CO2释放速率、累积释放量及有机碳矿化强度,均达到极显著差异,但两种生物炭处理与对照相比没有显著差异。在培养前期(30 d),不同物料均显著提高了土壤有机碳含量;但培养一年后,仅两种生物炭处理土壤有机碳含量较高,秸秆及木质素与对照相比没有显著差异。秸秆和木质素能显著增加DOC、ROC和MBC等土壤活性有机碳含量,而两种生物炭与对照相比没有明显差异;土壤DOC、ROC(167 mmol·L-1KMn O4)、ROC(33mmol·L-1KMn O4)和MBC直接影响CO2累积释放量,ROC(333 mmol·L-1KMn O4)对CO2累积释放量具有较强的间接作用。相对于秸秆和木质素而言,生物炭增加土壤有机碳含量,而没有增加CO2释放量,因此生物炭农用在固碳减排方面更具有积极意义。

Additions of organic materials could enhance soil organic carbon and may also promote carbon dioxide(CO2)emissions. In an incubation experiment, we examined the CO2 emissions and organic carbon contents of fluvo-aquic soil after applying straw and lignin and their biochars. The rate and cumulative amount of CO2 emissions and the dynamic changes of total organic carbon, dissolved organic carbon(DOC), readily oxidation carbon(ROC)and microbial biomass carbon(MBC)were measured. Compared with the control, the rate and accumulative amount of CO2 emissions, and organic carbon mineralization intensity were all significantly increased by straw or lignin additions,but not by their biochars. During the first 30 d incubation, all materials significantly increased soil organic carbon. After one year, however,higher soil organic carbon was found only in the biochar treatments. Straw or lignin additions significantly promoted DOC, ROC and MBC,but their biochars did not. The accumulative emissions of soil CO2 were influenced directly by soil DOC, ROC(176 mmol·L-1KMn O4), ROC(33 mmol·L-1KMn O4), and indirectly by ROC(333 mmol·L-1KMn O4). These results suggest that agricultural applications of biochars have positive roles in promoting carbon sequestration and reducing CO2 emissions.