Effects of plastic film mulching on soil greenhouse gases (CO2, CH4 and N2O) concentration within soil profiles in maize fields on the Loess Plateau, China

To better understand the effects of plastic film mulching on soil greenhouse gases (GHGs) emissions, we compared seasonal and vertical variations of GHG concentrations at seven soil depths in maize (Zea mays L.) fields at Changwu station in Shaanxi, a semi-humid region, between 2012 and 2013. Gas samples were taken simultaneously every one week from non-mulched (BP) and plastic film-mulched (FM) field plots. The results showed that the concentration of GHGs varied distinctly at the soil-atmosphere interface and in the soil profile during the maize growing season (MS). Both carbon dioxide (CO2) and nitrous oxide (N2O) concentrations increased with increasement of soil depth, while the methane (CH4) concentrations decreased with increasement of soil depth. A strong seasonal variation pattern was found for CO2 and N2O concentrations, as compared to an inconspicuous seasonal variation of CH4 concentrations. The mean CO2 and N2O concentrations were higher, but the mean CH4 concentration in the soil profiles was lower in the FM plots than in the BP plots. The results of this study suggested that plastic film mulching significantly increased the potential emissions of CO2 and N2O from the soil, and promoted CH4 absorption by the soil, particularly during the MS.

为了更好地理解塑料薄膜覆盖对土壤温室气体（GHGs）排放的影响，我们比较了2012年至2013年期间在陕西长武站（一个半湿润地区）玉米（Zea mays L.）田7个土壤深度处温室气体浓度的季节变化和垂直变化。每周同时从无覆盖（BP）和塑料薄膜覆盖（FM）的农田地块采集气体样本。结果表明，在玉米生长季（MS）期间，土壤 - 大气界面和土壤剖面中的温室气体浓度存在明显差异。二氧化碳（CO₂）和氧化亚氮（N₂O）浓度随土壤深度增加而升高，而甲烷（CH₄）浓度随土壤深度增加而降低。与甲烷浓度不明显的季节变化相比，二氧化碳和氧化亚氮浓度呈现出强烈的季节变化模式。土壤剖面中平均二氧化碳和氧化亚氮浓度在FM地块中较高，而平均甲烷浓度在FM地块中比在BP地块中低。本研究结果表明，塑料薄膜覆盖显著增加了土壤中二氧化碳和氧化亚氮的潜在排放，并促进了土壤对甲烷的吸收，尤其是在玉米生长季期间。