地膜覆盖对菜地土壤剖面温室气体的影响

为了解地膜覆盖对菜地剖面温室气体的影响，本研究利用扩散箱法测定了2014-2015年西南地区辣椒-萝卜轮作菜地10、20和30 cm土壤剖面的CH₄、CO₂和N₂O的浓度.结果表明，整个观测季覆膜（F）和不覆膜（NF）处理土壤剖面的CH₄浓度均随土壤深度增加而降低.与NF相比，覆膜极显著提高了辣椒季30 cm土层的CH₄浓度（p<0.01），但极显著降低了萝卜季20 cm土层的CH₄浓度（p<0.01），且对观测季其他土层的CH₄浓度无显著影响（p>0.05）；与CH₄相反，整个观测季覆膜和不覆膜处理土壤剖面的CO₂浓度均随土壤深度增加而增加.与NF相比，覆膜显著提高了辣椒季30 cm土层和萝卜季各土层的CO₂浓度（p<0.05）；与CO₂相似，整个观测季节覆膜和不覆膜处理土壤剖面的N₂O浓度均随土壤深度增加而增加.与NF相比，覆膜对辣椒季各土层的N₂O浓度影响不显著（p<0.05），却显著增加了萝卜季各土层的N₂O浓度（p<0.05）.总之，在辣椒季，地膜覆盖有利于深层土壤（30 cm） CH₄和CO₂的积累，而对N₂O的影响却不显著.在萝卜季，地膜覆盖不利于中层土壤（20 cm） CH₄的积累，但有利于各土层CO₂和N₂O的积累.Pearson相关性分析结果表明，在辣椒季，各处理10 cm土层的CH₄浓度与土壤充水孔隙度（WFPS）呈显著正相关（p<0.05），各处理10 cm土层的CO₂浓度与各环境因子相关性均不显著（p>0.05）.与CO₂类似，覆膜处理10 cm土层的N₂O浓度与各环境因子相关性不显著（p>0.05），但不覆膜处理10 cm土层的N₂O浓度与WFPS呈显著正相关（p<0.05）.在萝卜季，各处理10 cm土层的CH₄浓度与各环境因子相关性不显著（p>0.05），各处理10 cm土层的CO₂和N₂O浓度与地下10 cm温度和土壤氮素呈显著正相关（p<0.05）.WFPS是影响10 cm土层CH₄浓度的主要因素，土壤温度和土壤氮素是影响10 cm土层CO₂浓度的主要因素，WFPS、土壤温度和土壤氮素是影响10 cm土层N₂O浓度的主要因素.

Effects of plastic film mulching on greenhouse gases in vegetable soil profiles

In order to understand the effect of plastic film mulching on greenhouse gases in vegetable soil profiles, the concentration of CH₄, CO₂ and N₂O in soils with depth of 10, 20 and 30 cm profiles of pepper-radish rotation vegetable fields in southwestern China were measured by diffusion box method during 2014-2015. The results showed that the CH₄ concentration of the treated soil profiles with film mulching (F) and no film mulching (NF) decreased with increasing soil depth during the whole observation period. Compared with NF, the film mulching significantly increased CH₄ concentration in 30 cm soil layer in pepper growing season (p<0.01), but significantly decreased CH₄ concentration in 20 cm soil layer in radish growing season (p<0.01), and had no significant effect on CH₄ concentration in other soil layer during observation season (p>0.05); Contrary to CH₄, the CO₂ concentrations of the F and NF-treated soil profiles increased with increasing soil depth during the whole observation period. Compared with NF, the film mulching significantly increased the CO₂ concentration in the soil layer of 30 cm in pepper growing season and the all soil layers of radish growing season (p<0.05); Similar to CO₂, the N₂O concentrations of the F and NF-treated soil profiles increased with increasing soil depth during the entire observation season. Compared with NF, the influence of film mulching on N₂O concentration in soil layers was not significant (p<0.05) in pepper growing season. However, it significantly increased the N₂O concentration of all soil layers in radish growing season (p<0.05). In short, in the pepper growing season, mulching film is beneficial to the accumulation of CH₄ and CO₂ in the deep soil (30 cm), but the effect on N₂O is not significant. In the radish season, plastic film mulching is not conducive to the accumulation of CH₄ in the middle soil (20 cm), but it is conducive to the accumulation of CO₂ and N₂O in each soil layer. Pearson correlation analysis results showed that, in the pepper growing season, the CH₄ concentrations of the F and NF-treated 10cm soil profile were significantly positively correlated with the soil water filled pore space (WFPS) (p<0.05), while the CO₂ concentrations of the F and NF-treated 10cm soil profile were not significantly correlated with various environmental factors (p>0.05). Similar to CO₂, the N₂O concentration of the F-treated 10cm soil profile was not significantly correlated with various environmental factors (p>0.05), but the N₂O concentration of the NF-treated in 10cm soil profile was significantly positively correlated with WFPS (p<0.05). In the radish growing season, the CH₄ concentrations of the F and NF-treated 10cm soil profile were not significantly correlated with various environmental factors (p>0.05). The CO₂ and N₂O concentrations of the F and NF-treated 10 cm soil profile were significantly positively correlated with the temperature of 10 cm underground and soil nitrogen (p<0.05). The effect of plastic film mulching on the greenhouse gases concentration of soil profiles is not consistent in different planting seasons WFPS is the main factor affecting the concentration of CH₄ in the 10 cm profile. Soil temperature and soil nitrogen are the main factors affecting the concentration of CO₂ in the 10 cm profile. WFPS, soil temperature and soil nitrogen are the main factors affecting the concentration of N₂O in the 10cm profile.