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pH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。
英文摘要:
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 CO_2 and N_2O 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 CO_2 and N_2O fluxes trends were generally the same throughout the whole rotation period. After applying the biochar,the CO_2 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 CO_2 cumulative emissions,with an increase of 42.9%. The N_2O flux results showed that the C2 treatment significantly (P < 0.05) reduced cumulative N_2O emissions,but increased the comprehensive warming potential of CO_2 and N_2O emissions. In contrast,the C1 and SR treatments had no significant effect on cumulative N_2O emissions and the comprehensive warming potential. The correlation analysis showed that CO_2 flux was significantly positively (P < 0.01) correlated with soil temperature and soil water content,and that the N_2O flux was significantly positively (P < 0.01) correlated with soil temperature,soil water content,NO_3~- -N,and NH_4~+ -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.