[Effects of Plastic Film Mulching and Nitrogen Fertilizer Application on CH Emissions from a Vegetable Field].

To investigate the effects of plastic film mulching and nitrogen fertilizer application on CH emissions from a vegetable field, static opaque and gas chromatography methods were applied, and 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 CH 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 CH emissions from the vegetable fields between the mulching methods. From May 2014 to April 2016, the annual average cumulative absorption of CH 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, respectively. The average annual cumulative uptake of CH under conventional planting was 40.76, 63.56, 62.77, and 21.92 mg·m, respectively. Different nitrogen application gradients had no significant effect on CH emissions from vegetable fields. There was a significant positive correlation between CH uptake and soil temperature, and a significant negative correlation between CH 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.