添加生物炭对海南燥红壤N2O和CO2排放的影响

为探讨海南燥红壤N_2O和CO_2排放对生物炭添加的响应,通过室内培养试验分析生物炭加入后对土壤化学性质、NH_4~+-N和NO_3~--N含量以及N_2O和CO_2排放通量及累积排放量的影响。试验设置CK(不施生物炭)、B1(2%生物炭)、B2(4%生物炭)、B3(6%生物炭)4个处理。结果表明:添加生物炭后,土壤有机质、全氮和速效钾含量显著提高,较CK增幅分别为67.4%～246.6%、38.6%～90.9%和696.0%～1 764.7%。相比于CK,不同量生物炭添加后均导致了NH_4~+-N和NO_3~--N含量降低,总体上,不同处理NH_4~+-N浓度表现为CKB3B2B1,NO_3~--N含量表现为CKB1B2B3;随培养时间增加,各处理NH_4~+-N浓度呈下降趋势,NO_3~--N含量呈上升趋势。生物炭施用延后了N_2O排放通量出现峰值的时间。各处理之间N_2O和CO_2排放通量的变化过程大致表现出一致的趋势,即随培养时间延长,N_2O排放通量先升高后降低,CO_2排放通量先升高后趋于稳定。和CK相比,生物炭添加不同程度地促进了N_2O和CO_2排放,B1、B2和B3处理下N_2O累积排放量分别增加了399.2%、494.2%和194.5%,CO_2排放总量分别增加了87.6%、153.3%和147.6%。本研究结果显示,生物炭施用短期内促进了土壤N_2O和CO_2的排放通量。

Effects of biochar addition on N2O and CO2 emissions in Hainan dry red soil

To investigate the response of N₂O and CO₂ emissions to biochar addition in dry red soil in Hainan, the effects of biochar addition on soil chemical properties, ammonium nitrogen and nitrate content, N₂O and CO₂ emission fluxes, and cumulative emissions were analyzed through laboratory incubation experiments. Four treatments were set up:CK(no biochar), B1(2% biochar), B2(4% biochar), and B3(6% biochar). The results showed that the content of soil organic matter, total nitrogen, and available potassium increased significantly by 67.4%~246.6%, 38.6%~90.9%, and 696.0%~1 764.7%, respectively, compared with CK,and the content of NH₄⁺-N and NO₃^--N decreased after the addition of biochar. In general, the concentration of NH₄⁺-N in the different treatments was CK>B3>B2>B1, and the content of NO₃^--N was CK>B1>B2>B3. With the extension of incubation time, the concentration of NH₄⁺-N in each treatment decreased, while the concentration of NO₃^--N increased. Biochar application delayed the peak N₂O emission flux. Variations in N₂O and CO₂ emission fluxes among different treatments showed a consistent trend; that was, with the extension of incubation time, N₂O and CO₂ emission fluxes first increased and then decreased, and then increased again with the extension of incubation time. Compared with CK, the addition of biochar promoted N₂O and CO₂ emissions to some degree, the cumulative N₂O emissions increased by 399.2%, 494.2%, and 194.5% under treatments B1, B2, and B3, respectively, and the total CO₂ emissions increased by 87.6%, 153.3%, and 147.6%, respectively. The results show that biochar application increase N₂O and CO₂ emissions in the short term.