运用“碳足迹”的方法评估小麦秸秆及其生物质炭添加对农田生态系统净碳汇的影响

为分析添加秸秆、生物质炭后小麦生产过程中碳足迹的动态、分布以及构成,研究了不同处理在小麦生长期的CO2、N_2O、CH4排放情况,以及不同处理的单位面积碳足迹构成与碳足迹总量,试验设置5个处理:对照(CK)、常规施肥(N)、施肥并添加4 t·hm-2秸秆(NS)、施肥并添加4 t·hm-2生物质炭(NBClow)、施肥并添加8 t·hm-2生物质炭(NBChigh)。结果表明,小麦生产中碳足迹的构成主要为农田生态系统净初级生产力(NPP)和氮肥生产过程中的能源消耗,与常规施肥相比:添加4 t·hm-2秸秆、4 t·hm-2生物质炭与8 t·hm-2生物质炭处理,小麦产量分别增加了30.9%、66.3%和36.6%;添加4 t·hm-2秸秆使土壤CO2的季节排放总量增加了68.7%,生态系统N_2O的季节排放总量降低了33.9%,添加4 t·hm-2和8 t·hm-2生物质炭生态系统N_2O的季节排放总量降低了23.8%和58.6%,但是土壤CO2的季节排放总量没有显著性的差异;添加4 t·hm-2秸秆使小麦生产过程中的碳足迹升高了26.0%,添加4 t·hm-2和8 t·hm-2生物质炭碳足迹分别降低了198.0%和112.9%。生物质炭的添加降低了小麦生产过程中的碳足迹。

Assessment of wheat straw and its biochar effects on carbon sink in agricultural ecosystems using "carbon footprint"method

This study assessed the dynamic, distribution and composition of carbon footprints in wheat production process under applications of wheat straw and its biochar using "carbon footprint" method. Crop yields and N₂O, CH₄ and CO₂ fluxes during wheat growth period were measured in five field treatments:control(CK), conventional fertilization(N), N plus 4 t·hm^-2 straw(NS) amendment, N plus 4 t·hm^-2 biochar(NBC_low) amendment, and N plus 8 t·hm^-2 biochar(NB_Chigh) amendment. The energy consumption in each step of wheat production process was also analyzed to calculate the carbon footprint. Results showed that the carbon footprint in wheat production was mainly net primary production and energy consumption related to fertilizer production. Compared with the conventional fertilization, Wheat yields in NS, NBC_low and NB_Chigh treatments increased 30.9%, 66.3% and 36.6%, respectively; The seasonal amounts of soil CO₂ emissions increased by 68.7% in NS treatment, but had no significant difference in biochar treatments. Cumulative N₂O emission was reduced by 33.9%, 23.8% and 58.6% under NS, NBC_low and NB_Chigh treatments, respectively; The carbon footprint increased by 26.0% in NS treatment, but reduced by 198.0% and 112.9% in NBC_low and NB_Chigh treatments, respectively. These findings indicate that applying wheat straw biochar reduces carbon footprint in the agricultural ecosystems.