地膜覆盖和施氮对菜地CH4排放的影响

以位于西南大学农业部重庆紫色土生态环境重点野外科学观测试验站内辣椒-萝卜轮作菜地为研究对象,采用静态暗箱/气相色谱法,进行为期2 a的田间原位观测,探讨地膜覆盖和不同施氮处理对菜地CH_4排放的影响.本实验设置8个处理,分别为对照常规(NN0)、对照覆膜(FN0),低N常规(NN1)、低N覆膜(FN1),中N常规(NN2)、中N覆膜(FN2),高N常规(NN3)、高N覆膜(FN3),研究地膜覆盖和施氮对菜地CH_4的排放特征和影响因素以及土壤碳氮组分的变化规律.结果表明,覆膜与常规两种种植方式对于菜地CH_4的排放没有明显差异. 2014年5月～2016年4月,覆膜种植下无氮、低氮、中氮和高氮菜地CH_4年均累积吸收量分别为28. 96、51. 90、43. 43和34. 41 mg·m~(-2),常规种植下CH_4年均累积吸收量分别为40. 76、63. 56、62. 77和21. 92 mg·m~(-2).不同施氮梯度对于菜地CH_4的排放没有显著影响.菜地CH4的吸收量与土壤温度呈显著正相关关系,与土壤含水率则呈现为显著负相关关系.地膜覆盖在辣椒季加速了土壤碳素的矿化,而在萝卜季则没有显著影响.

Effects of Plastic Film Mulching and Nitrogen Fertilizer Application on CH4 Emissions from a Vegetable Field

To investigate the effects of plastic film mulching and nitrogen fertilizer application on CH₄ emissions from a vegetable field, static opaque and gas chromatography methods were applied, and in situ field observations of a chili-radish rotation system, from May 2014 to April 2016, were carried out in the Key Field Station for Monitoring of Eco-Environment of Purple Soil of the Ministry of Agriculture of China in the farm of Southwest University in Chongqing. Eight treatments were set up in the field experiment:control routine (no N application and no plastic film mulching) (NN0), control mulching (FN0), low N routine (NN1), low N mulching (FN1), conventional N routine (NN2), conventional N mulching (FN2), high N routine (NN3), and high N mulching (FN3). The characteristics and influencing factors of CH₄ emissions and the changes of soil carbon and nitrogen composition from all treatments were studied. The results showed that there was no significant difference in the CH₄ emissions from the vegetable fields between the mulching methods. From May 2014 to April 2016, the annual average cumulative absorption of CH₄ in nitrogen-free, low-nitrogen, medium-nitrogen, and high-nitrogen vegetable fields under film-mulching cultivation was 28.96, 51.90, 43.43, and 34.41 mg·m^-2, respectively. The average annual cumulative uptake of CH₄ under conventional planting was 40.76, 63.56, 62.77, and 21.92 mg·m^-2, respectively. Different nitrogen application gradients had no significant effect on CH₄ emissions from vegetable fields. There was a significant positive correlation between CH₄ uptake and soil temperature, and a significant negative correlation between CH₄ and soil water content. Plastic film coverage accelerated the mineralization of soil carbon in the pepper season, but there was no significant effect in the radish season.