Eeffect Of Plastic Film Mulching And Nirogen Appling On Greenhouse Gases Emissions In Dryland Maize Field

Plastic film mulching and nitrogen applying have been used to improved crop production, but few studies have focused on the effects of plastic film mulching and nitrogen rate on greenhouse gases（GHGs, including N₂O, CO₂, and CH₄） emissions. Understanding the response of GHGs to plastic film mulching and nitrogen rate is beneficial for improving management practices. To solve these problems, we performed field experiment to measure the annual GHGs emissions using the static chamber technique from 2014 to 2015 in Changwu ecological experimental station. The objective of this study was to assess the effects of plastic film mulching and different nitrogen levels（treatments with different nitrogen under plastic film mulching and non-mulched are labled FM0、FM100、FM250、FM400、BP0、BP100、BP250 and BP400, respectively） on greenhouse gas emission in rainfed spring maize field. The main results of this study were concluded as follows:1. The N fertilization significantly increased the N₂O emission rate both at plastic film mulching（FM） and non-mulched（BP） treatments. The cumulative N₂O emissions showed no difference beteween BP and FM treatments, while the ratios of cumulative N₂O emissions at different stages to the total N₂O emissions during the whole growing season were different. The plastic film mulching increased the ratios of cumulative N₂O emissions during VE-V10 stage, ranging from 36% to 51%. The non-mulched treatments increased the ratios of cumulative N₂O emissions during V10-R6 stage, ranging from 64% to 76%. The N₂O emissions significantly positive correlated with soil NO₃^--N and H₄⁺-N content.2. Plastic mulching significantly increased the cumulative CO₂ emissions by 8%-39%. The ratios of cumulative CO₂ emissions at different stages to the total CO₂ emissions during the whole growing season were changed at plastic film mulching treatments. The plastic film mulching increased the ratios of cumulative CO₂ emissions during VE-V10 stage, ranging from 41% to 43%. The non-mulched treatments increased the ratios of cumulative CO₂ emissions during VT-R6 stage, ranging from 38% to 45%. The CO₂ emissions significantly positive correlated with the soil temperature and soil NO₃^--N and NH₄⁺-N content, while significantly negative correlated with the WFPS.3. The ratios of cumulative CH₄ absorptions during fallow stage to the whole stage were 48-60%. The cumulative CH₄ absorptions showed no difference both beteween BP and FM treatments and different N application rate.4. Plastic mulching significantly increased the maize yield. Both the GWP and GHG intensity increased as the N application rate increased. We achieved higher yield and lower GHG intensity using 250 kg hm-2 N fertilizer under plastic film mulching practice.