膜下滴灌对土壤CO2与CH4浓度的影响

摘要

A pot experiment was conducted in a greenhouse to compare the influences of flood (F) and drip (D) irrigations on soil concentrations of CO2 and CH4 during potato cropping season using the static opaque chamber and gas chromatography technique. Two agronomic measures were evaluated for each irrigation regime under mulched (M) and non-mulched conditions. Three more treatments were set under mulched drip irrigation (MD) based on different wet ratio (P) - PI (P=25%), P2 (P=33%) and P3 (P=50%). There were six treatments altogether, denoted as DPI, MDP1, MDP2, MDP3, FC and ME Bare soils with (MBS) and without (BS) plastic film mulching were set as control treatments. Results suggested that mulching treatments increased soil CO2 concentration by 10.4%~94.5% due to plastic film mulching increasing effect on temperature and moisture, and barrier effects on natural air transmission of the soil-atmosphere system. Mulching treatments decreased soil CH4 concentration by 5.1%~47.4%. Because of dry-wet alternation under drip-irrigation and decreased soil aeration under flood irrigation, CO2 concentration was 7.4%~49.7% higher under flood irrigation and CH4 concentration 6.6%~68.2% lower under drip irrigation. Soil moisture influenced greenhouse gas emission by altering soil aeration and soil dissolved organic matter. The higher the wet ratio under MD, the lower was CO2 concentration. However, the effect of wet ratio on CH4 concentration was not clear. Soil temperature was the main driving factor of soil respiration, which also regulated CH4 oxidation processes. The greenhouse gas concentration in soils after DPI irrigation showed a significant positive correlation between soil temperature and soil CO2 concentration. Also after DPI irrigation, a significant negative correlation existed between soil temperature and soil CH4 concentration while a significant negative correlation was noted between soil CO2 and CH4 concentrations.%在温室进行了马铃薯盆栽试验,采用静态暗箱-气相色谱法比较了滴灌(D)和漫灌(F)两种不同灌溉制度对土壤CO2与CH4浓度的影响.在每种灌溉制度下再分设覆膜(M)与不覆膜两种农艺措施处理.覆膜滴灌(MD)下按土壤湿润比(P)不同,再设3个处理,分别为P1 (P=25％)、P2 (P=33％)、P3 (P=50％),共6个处理,即DP1、MDP1、MDP2、MDP3、FC(不覆膜漫灌)和MF(覆膜漫灌),裸土(BS)和覆膜裸土(MBS)为对照.研究结果表明:覆膜的增温保湿作用及薄膜对土壤与大气间气体传输的自然阻隔作用使土壤CO2浓度升高10.4％～94.5％,CH4浓度降低5.1％～47.4％.滴灌的干湿交替现象以及漫灌对土壤通气性的降低使漫灌处理土壤中CO2浓度高于滴灌7.4％～49.7％,CH4浓度降低6.6％～68.2％.而土壤湿度通过影响土壤通气性和土壤溶解性有机质两方面来影响土壤温室气体排放,覆膜滴灌下湿润比越高,土壤中CO2浓度越低,其对CH4浓度的影响不确定.土壤温度是土壤呼吸的主要驱动因子,也会影响CH4的氧化过程.观察DP1处理灌水后土壤中温室气体浓度发现,CO2浓度与温度呈显著正相关关系,CH4浓度与温度呈显著负相关关系,土壤中CO2浓度与CH4浓度呈显著负相关关系.