地膜覆盖对菜地垄沟CH4和N2O排放的影响

Effect of Plastic Film Mulching on Methane and Nitrous Oxide Emissions from the Ridges and Furrows of a Vegetable Field

为了探讨地膜覆盖对菜地垄沟温室气体CH4和N2O排放的影响,以位于西南大学农业部重庆紫色土生态环境重点野外科学观测试验站内辣椒-萝卜轮作菜地为研究对象,采用静态暗箱/气相色谱法,进行为期1 a的田间原位观测.本试验设置常规和覆膜两种处理方式,研究地膜覆盖对菜地垄沟中CH4和N2O排放的影响.结果表明,地膜覆盖能极显著提高土壤全年pH(P<0.01),显著提高全年的地表温度和地下5 cm温度(P<0.05),显著提高萝卜季土壤含水率(P<0.05).不论是辣椒季还是萝卜季,覆膜显著降低了垄的CH4排放(P<0.05),辣椒季垄的CH4平均排放通量常规和覆膜处理分别为0.110mg·(m^(2)·h)^(-1)和0.028 mg·(m^(2)·h)^(-1),萝卜季分别为0.011 mg·(m^(2)·h)^(-1)和-0.019 mg·(m^(2)·h)^(-1),但覆膜对沟的CH4排放没有显著影响(P>0.05),辣椒季常规和覆膜处理分别为0.058 mg·(m^(2)·h)^(-1)和0.057 mg·(m^(2)·h)^(-1),萝卜季分别为0.083mg·(m^(2)·h)^(-1)和0.092 mg·(m^(2)·h)^(-1),对比垄和沟,除了辣椒季常规处理下垄CH4排放量显著高于沟,其它均为沟显著高于垄,这与西南地区较高的降雨量下沟内较稳定的缺氧环境有关.覆膜处理对N2O没有显著影响,辣椒季垄N2O的平均排放通量常规和覆膜处理下分别为65.41μg·(m^(2)·h)^(-1)和68.39μg·(m^(2)·h)^(-1),萝卜季分别为78.43μg·(m^(2)·h)^(-1)和66.19μg·(m^(2)·h)^(-1),辣椒季沟N2O的平均排放通量分别为19.82μg·(m^(2)·h)^(-1)和22.85μg·(m^(2)·h)^(-1),萝卜季分别为35.80μg·(m^(2)·h)^(-1)和40.00μg·(m^(2)·h)^(-1),均无显著差异(P>0.05),对比垄和沟,垄N2O的排放量显著高于沟,N2O主要由垄向大气排放.CH4排放通量与地表及地下5 cm温度呈显著正相关,N2O的排放通量仅与碱解氮和铵态氮含量呈显著正相关.

Investigate the effects of plastic film mulching on CH4and N2O emissions from a vegetable field,a one-year in situ field observation was conducted using a static opaque chamber in a pepper-radish cropping system at the Key Field Station for Monitoring of Eco-Environment of Purple Soil of the Ministry of Agriculture of China at Southwest University,Chongqing.Two treatments(conventional and film mulching)were used to study the influence of film mulching on CH4and N2O emissions.The results showed that mulching significantly increased the annual average soil pH(P<0.01),annual surface and subsurface(5 cm)temperature(P<0.05),and soil moisture content during the radish-growing season(P<0.05).The mulching also significantly reduced CH4emissions in the field ridges(P<0.05);the average CH4flux from ridges during the pepper-growing season was 0.110 mg·(m^(2)·h)^(-1)and 0.028 mg·(m^(2)·h)^(-1),and 0.011 mg·(m^(2)·h)^(-1)and-0.019 mg·(m^(2)·h)^(-1)during the radish-growing season,under the conventional and film mulching treatments,respectively.However,across the entire experiment,CH4flux from field furrows was not significantly different between the two mulching treatments(P>0.05),with mean flux values during the pepper-growing season of 0.058 mg·(m^(2)·h)^(-1)and 0.057 mg·(m^(2)·h)^(-1),and 0.083 mg·(m^(2)·h)^(-1)and 0.092 mg·(m^(2)·h)^(-1)during the radish-growing season,for conventional and plastic film mulching,respectively.Except for the conventional treatment during the pepper-growing season,CH4emissions from ridges were significantly higher than from furrows,but for other treatments,including conventional and film mulching treatments during radish-growing season and film mulching treatment during the pepper-growing season,the CH4emissions from furrows were all significantly higher than those from ridges.This was related to the stable anoxic environment created in furrows under high rainfall conditions in Southwest China.The N2O emission flux from the ridges during the pepper-growing season was 65.41μg·(m^(2)·h)^(-1)and 68.39μg·(m^(2)·h)^(-1)under the conventional and film mulching treatments,respectively,and the N2O emission flux during the radish-growing season was 78.43μg·(m^(2)·h)^(-1)and 66.19μg·(m^(2)·h)^(-1),respectively.The N2O flux between conventional treatment and film mulching treatment in ridges or furrows were not significantly different(P>0.05),while the N2O emissions from the ridges were significantly higher than that from the furrows.CH4emission flux was significantly positively correlated with surface and subsurface temperature,while N2O emission flux was only significantly positively correlated with alkaline nitrogen and ammonium nitrogen content.