施用生物炭和秸秆还田对华北农田CO2、N2O排放的影响

以华北农田冬小麦-夏玉米轮作体系连续6a施用生物炭和秸秆还田的土壤为研究对象,于2013年10月—2014年9月,采用静态暗箱-气相色谱法,对CO_2、N_2O通量进行了整个轮作周期的连续观测,探究施用生物炭与秸秆还田对其排放通量的影响。试验共设4个处理:CK(对照)、C1(低量生物炭4.5 t hm~(-2)a~(-1))、C2(高量生物炭9.0 t hm~(-2)a~(-1))和SR(秸秆还田straw return)。结果表明:在整个轮作周期内,各处理CO_2、N_2O通量随时间的变化趋势基本一致。随着生物炭施用量的增加,CO_2排放通量分别增加了0.3%—90.3%(C1)、1.0%—334.2%(C2)和0.4%—156.3%(SR)。其中,C2处理对CO_2累积排放量影响最大,增幅为42.9%。对N_2O而言,C2处理显著降低了N_2O累积排放量,但增加了CO_2和N_2O排放的综合增温潜势,C1和SR处理对N_2O累积排放量及综合增温潜势均没有显著影响。相关分析表明,土壤温度和土壤含水量是影响CO_2通量最主要的因素,两者之间呈极显著的正相关关系;N_2O通量与土壤温度、土壤含水量、NO_3~--N和NH_4~+-N均表现出极显著的正相关关系,而与土壤p H值表现出极显著的负相关关系。由此可见,添加生物炭对于减少氮素的气体损失具有较大的潜力。

Effects of biochar and straw return on CO2 and N2O emissions from farmland in the North China Plain

A 6-year biochar and straw return experiment with a winter wheat-summer maize rotation system in the North China Plain investigated the effects of biochar and straw return on CO₂ and N₂O fluxes using the static chamber/gas chromatography method. The experiment consisted of four treatments with three replicates. The treatments were CK (control), C1 (biochar 4.5 t hm^-2 a^-1), C2 (biochar 9.0 t hm^-2 a^-1), and SR (straw return). The results showed that the CO₂ and N₂O fluxes trends were generally the same throughout the whole rotation period. After applying the biochar, the CO₂ fluxes increased 0.3%-90.3% (C1), 1.0%-334.2% (C2), and 0.4%-156.3% (SR). The C2 treatment had the greatest effect on CO₂ cumulative emissions, with an increase of 42.9%. The N₂O flux results showed that the C2 treatment significantly (P < 0.05) reduced cumulative N₂O emissions, but increased the comprehensive warming potential of CO₂ and N₂O emissions. In contrast, the C1 and SR treatments had no significant effect on cumulative N₂O emissions and the comprehensive warming potential. The correlation analysis showed that CO₂ flux was significantly positively (P < 0.01) correlated with soil temperature and soil water content, and that the N₂O flux was significantly positively (P < 0.01) correlated with soil temperature, soil water content, NO^- ₃-N, and NH₄⁺-N, but significantly negatively (P < 0.01) correlated with soil pH. In summary, the addition of biochar has the potential to significantly reduce nitrogen gas loss.