基于不同施肥模式添加生物炭后菜地土壤CO_2释放特征及不同形态碳含量变化

Characteristics of CO_2 Emissions and Changes in Carbon Fractions after Application of Biochar Under Various Fertilization Regimes in Vegetable Soil

【目的】研究4种常规施肥模式下,添加生物炭后菜地土壤(褐潮土)CO_2释放量、可溶性有机碳(DOC)和微生物生物量碳(SMBC)含量的变化,阐明添加生物炭对土壤CO_2释放及不同形态碳的影响。【方法】采用室内恒温好氧培养-气象色谱测定方法,在不施肥(CK)、施有机肥(M)、施化肥(F)、有机无机混施(M+F)4种模式下投入2%和4%(质量比:生物炭/土壤干重)生物炭,定期采集气样和土样,分析土壤CO_2的释放量及DOC、SMBC含量的动态变化,并分析DOC、SMBC含量变化与CO_2释放量变化之间的相关关系。【结果】在F和M+F基础上,添加生物炭处理的土壤CO_2释放速率在培养前期(2—8 d)显著高于未添加生物炭处理,而在10—60 d,二者CO_2释放速率无显著差异;在CK和M基础上,添加与未添加生物炭处理在整个培养期间CO_2释放速率没有显著差异。在CK基础上,添加2%和4%生物炭后CO_2累积释放量分别为2 839和3 272 mg·kg^(-1),与CK(3 134 mg·kg^(-1))相比均无显著差异;而在F和M+F基础上,添加2%和4%生物炭后CO_2累积释放量均显著提高,分别提高20.6%和19.8%、29.9%和40.7%。相关分析表明,未添加生物炭处理DOC、SMBC含量与CO_2释放量之间无相关关系,而添加生物炭处理DOC、SMBC含量与CO_2释放量极显著相关。【结论】将生物炭单独投入未施肥土壤中,土壤CO_2排放量未出现明显增加或降低;在有机肥基础上添加生物炭,土壤CO_2排放量随着生物炭投入量的增加而增加;在化肥、有机无机配施基础上添加生物炭后,土壤CO_2排放增加比例最高。

[ Objective ] In order to clarify the effects of application of biochar on soil CO2 emissions and changes in different forms of organic carbon, soil CO2 emissions and dynamics of dissolved organic carbon （DOC） and microbial biomass carbon （SMBC） were measured after application of biochar under various fertilization regimes. [ Method ] An incubation was designed to investigate the CO2 emission and dynamics of DOC and SMBC after application of 2% （biochar/dry soil） and 4% biochar under various fertilization regimes （no fertilizer （CK）, organic manure （M）, inorganic fertilizer （F）, M＋F）. The correlation among DOC, SMBC and CO2 were analyzed. [Result] In the F and M＋F treatments added with biochar, soil CO2 emission rates in the earlyperiod （2-8 d） was significantly higher than those without adding biochar, while during the 10-60 d, CO2 release rates in both treatments were no significant differences. In the CK and M treatments, the CO2 emission rates were no significant differences between the treatments with or without adding biochar throughout the incubation. In CK treatment, the cumulative CO2 emission with application of biochar was not differed with that without biochar. In the F and M＋F treatments, the cumulative CO2 emissions were significantly increased after application of 2% and 4% biochar （20.6% and 19.8%, 29.9% and 40.7%, respectively）. The correlation showed that there was no relationship between DOC/SMBC and CO2 emissions without adding biochar, however, there was an obvious correlation when biochar was applied. [ Conclusion ] Soil CO2 emissions did not change when biochar was applied to the unfertilized soil. However, the cumulative CO2 emission increased by application of biochar into the soil with manure application. Furthermore, the increment of CO2 emission was dramatically increased when biochar was applied into the soil with inorganic fertilizers plus manure.