沼液灌溉对冬小麦-夏玉米轮作农田CO_2、N_2O排放规律的影响

Effects of biogas slurry irrigation on CO_2 and N_2O emission from winter wheat-summer maize rotation farmland

为探究沼液灌溉对冬小麦-夏玉米轮作农田CO_2和N_2O排放特征及土壤理化性质的影响,设置不同的灌溉模式,即空白对照处理CK、常规施肥处理CF、灌溉两次(小麦季一次+玉米季一次)2∶1沼液处理T1、灌溉三次(小麦季两次+玉米季一次)2∶1沼液处理T2与灌溉三次(小麦季两次+玉米季一次)2∶1沼液处理T3共五个处理,采用静态箱-气相色谱法,研究牛场沼液灌溉条件下冬小麦-夏玉米轮作农田土壤CO_2和N_2O的排放特征,同时监测气象条件、土壤铵态氮、硝态氮、土壤可溶性有机碳等因子以及作物产量,分析并探讨了轮作周期内农田土壤CO_2和N_2O的排放特征及相关影响因子。试验结果表明,沼液灌溉没有改变轮作周期内土壤CO_2和N_2O排放通量的季节性变化规律,但会造成灌溉后短期内CO_2和N_2O排放通量增加;轮作周期内沼液灌溉处理在一定程度上提高了CO_2的排放水平,但除T3处理外,差异性均未达到显著水平;沼液灌溉处理没有明显提高N_2O排放水平。沼液灌溉提高了土壤可溶性有机碳含量,施用化肥会降低土壤可溶性有机碳含量;与常规施肥处理CF相比,T2、T3处理作物籽粒产量无明显差异,T1处理严重减产。综合考虑作物籽粒产量与CO_2和N_2O累积排放量,T2处理为本试验条件下最合理的沼液灌溉模式。

To investigate the effects of biogas slurry irrigation on CO2 and N2O emissions and soil physicochemical properties, in winter wheat-summer maize rotation system, five different irrigation modes were set up, including blank control（CK）, fertilization treatment（CF）,2∶1 biogas slurry irrigation for two times（one time in wheat season and one time in corn season）（T1）, 2∶1 biogas slurry irrigation for three times（two times in wheat season and one time in corn season）（T2）and 1∶1 biogas slurry irrigation for three times（two times in wheat season and one time in corn season）（T3）. In the study, Static-Gas Chamber method was applied to study the soil CO2 and N2O emission from winter wheat-summer maize rotation cropping system under the condition of marsh fluid biogas irrigation. The meteorological condition, soil ammonium nitrogen, nitrate nitrogen, soil soluble organic carbon and crop yield were also monitored. The characteristics of CO2 and N2O emissions from cropland soil and their influencing factors were analyzed and discussed, and a reasonable biogas slurry irrigation model was put forward. The results showed that the biogas irrigation did not affect the seasonal variation of soil CO2 and N2O emission flux during the rotation cycle, however, it could cause the short-term emission increase after irrigation. The CO2 emission level was increased by different biogas slurry irrigation treatments in a certain extent, but the difference was not significant except T3. The biogas irrigation treatments did not improve the N2 O emission level significantly. The content of soil soluble organic carbon was increased by biogas slurry irrigation treatments and was decreased with the application of chemical fertilizers. Compared with conventional fertilization treatment, there was no significant difference between the crop yield of T2 and T3, but the yield of T1 was significantly decreased. Considering the crop yield and CO2 and N2O accumulated emissions, T2 treatment was the most reasonable biogas slurry irrigation mode under this study condition.