Effects of plastic film mulching and nitrogen fertilization on the emissions of greenhouse gases from vegetable field in Southwest China

This study identified the influence of plastic film mulching (FM) and nitrogen (N) fertilization on the CH4 emission, the global warming potential (GWP) and the greenhouse gas intensity (GHGI) in a summer-hot pepper and winter-radish rotation field from May 2014 to April 2017. The experiment had 8 treatments including no-mulching (NM) and plastic film mulching with four different N fertilization rates (0, 150, 300 and 450 kg N ha(-1) and 0, 100, 200 and 300 kg N ha(-1) in the respective hot pepper and radish growing periods). The results indicated that FM as well as N fertilization had insignificant effects on CH4 emissions in the hot pepper and radish growing periods (P > 0.05). Relative to NM, FM had little effect on GWP (P > 0.05) but lowered GHGI substantially (P < 0.05) during the hot pepper growing period. During the radish growing period, FM enhanced GWP and GHGI significantly (P < 0.05). Additionally, N fertilization significantly enhanced GWP and vegetable yields both in hot pepper and radish growing periods (P < 0.05). In hot pepper growing period, N fertilization increased GWP more significantly than yield which resulted in increased GHGI with N fertilization rate, and the promotion effect of N fertilization on hot pepper yield was strongest at 150 kg N ha(-1) with a relatively low GHGI. However, in radish growing period, N fertilization increased yield more significantly than GWP which resulted in the decreasing effect of N fertilization on GHGI, and the promotion effect of N fertilization on radish yield was strongest at 300 kg N ha(-1) with a relatively low GHGI. Therefore, FM with 150 kg N ha(-1) and NM with 300 kg N ha(-1) were respectively recommended for the hot pepper growing period and radish growing period to achieve high vegetable yields and mitigate greenhouse gas (GHG) emissions simultaneously under the present vegetable field condition in Southwest China.