覆膜和氮肥用量对雨养春玉米农田甲烷吸收的影响

为了研究覆膜与氮肥用量对雨养春玉米农田CH_4吸收的影响,在覆膜(FM)与不覆膜(BP)条件下分别设置了0、100、250、400 kg·hm~(-2)4个氮肥水平,共8个处理,采用静态暗箱-气相色谱法对农田CH_4的吸收通量进行连续观测,同时观测影响通量变化的温度、水分以及硝铵态氮等环境因子。结果表明:旱作春玉米农田是甲烷的汇,休闲期的累积吸收量占年总吸收量48%~60%,在年总吸收量中占了不可忽视的一部分;FM0、FM100、FM250、FM400和BP0、BP100、BP250、BP400在2014—2015年的年总吸收量分别为0.99、1.38、1.3、1.37 CH_4-C kg·hm~(-2)和1.43、1.77、1.68、1.56 CH_4-C kg·hm~(-2),地膜覆盖和施氮量的增加均未显著改变雨养春玉米农田对CH_4的吸收量;雨养春玉米农田土壤CH_4的吸收速率与0、10 cm土层土壤温度呈极显著正相关,与土壤孔隙含水量(WFPS)、NH4+-N之间呈极显著负相关,不覆膜条件下与NO3--N之间呈负相关关系,且达到极显著水平(P0.01)。

Effect of film mulching and nitrogen fertilizer on CH4 absorption of rainfed spring maize farmland

Understanding the response of CH4 absorption to film mulching and nitrogen fertilizer is of value for improving management practices.We monitored the CH4 absorption from plastic film-mulched and no-mulched maize fields that received different N application rates (0,100,250 kg·hm-2 and 400 kg·hm-2) using the static chamber technique.In addition,the impact factors (soil inorganic nitrogen,soil temperature and moisture,etc.) were estimated.The results showed that the rain-fed maize fields acted as a sink for CH4,and 48％ ～ 60％ of the annual uptake was during the fallow period.The annual CH4 uptake rate was 0.99,1.38,1.3,1.37,1.43,1.77,1.68,1.56 CH4-C kg ·hm-2 for FM0,FM100,FM250,FM400,BP0,BP100,BP250 and BP400 treatment in 2014-2015,respectively.Both film mulching and N fertilizer did not increase the CH4 uptake.The soil C H4 uptake was positively correlated with 0 cm and 10 cm soil temperature,but negatively correlated with soil WFPS and soil NH4 +-N concentration.The CH4 up-take was negatively correlated with soil NO3--N concentration under no-mulched treatments.