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

Investigate the effects of plastic film mulching on CH₄ and 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 CH₄ and 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 CH₄ emissions in the field ridges (P<0.05); the average CH₄ flux from ridges during the pepper-growing season was 0.110 mg·(m²·h)^-1 and 0.028 mg·(m²·h)^-1, and 0.011 mg·(m²·h)^-1 and -0.019 mg·(m²·h)^-1 during the radish-growing season, under the conventional and film mulching treatments, respectively. However, across the entire experiment, CH₄ flux 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·(m²·h)^-1 and 0.057 mg·(m²·h)^-1, and 0.083 mg·(m²·h)^-1 and 0.092 mg·(m²·h)^-1 during the radish-growing season, for conventional and plastic film mulching, respectively. Except for the conventional treatment during the pepper-growing season, CH₄ emissions 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 CH₄ emissions 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 65.41 μg·(m²·h)^-1 and 68.39 μg·(m²·h)^-1 under the conventional and film mulching treatments, respectively, and the N₂O emission flux during the radish-growing season was 78.43 μg·(m²·h)^-1 and 66.19 μg·(m²·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. CH₄ emission 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.