施用生物炭和秸秆还田对华北农田CO_2、N_2O排放的影响

Effects of biochar and straw return on CO_2 and N_2O emissions from farmland in the North China Plain

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。

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^-2a^-1）,C2（ biochar 9.0 t hm^-2a^-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,NO3^--N,and NH4^＋-N,but significantly negatively（ P〈0. 01）correlated with soil p H. In summary,the addition of biochar has the potential to significantly reduce nitrogen gas loss.