Plastic film mulching application improves potato yields, reduces ammonia emissions, but boosts the greenhouse gas emissions in China

Abstract

With global population growth and climate change, food security and global warming have emerged as two major challenges to agricultural development. Plastic film mulching (PM) has long been used to improve yields in rain-fed agricultural systems, but few studies have focused on soil gas emissions from mulched rainfed potatoes on a long-term and regional scale. This study integrated field data with the Denitrification-Decomposition (DNDC) model to evaluate the impacts of PM on potato yields, greenhouse gas (GHG) and ammonia (NH₃) emissions in rainfed agricultural systems in China. We found that PM increased potato yield by 39.7 % (1505 kg ha^-1), carbon dioxide (CO₂) emissions by 15.4 % (123 kg CO₂ eq ha^-1), nitrous oxide (N₂O) emissions by 47.8 % (1016 kg CO₂ eq ha^-1), and global warming potential (GWP) by 38.9 % (1030 kg CO₂ eq ha^-1), while NH₃ volatilization decreased by 33.9 % (8.4 kg NH₃ ha^-1), and methane (CH₄) emissions were little changed compared to CK. Specifically, the yield after PM significantly increased in South China (SC), North China (NC), and Northwest China (NWC), with increases of 66.1 % (2429 kg ha^-1), 44.1 % (1173 kg ha^-1), and 43.6 % (956 kg ha^-1) compared to CK, respectively. The increase in GWP and greenhouse gas emission intensity (GHGI) under PM was more pronounced in the Northeast China (NEC) and NWC regions, with respective increases of 57.1 % and 60.2 % in GWP, 16.9 % and 10.3 % in GHGI. While in the Middle and Lower reaches of the Yangtze River (MLYR) and SC, PM decreased GHGI with 10.2 % and 31.1 %, respectively. PM significantly reduced NH₃ emissions in all regions and these reductions were most significant in Southwest China (SWC), SCand MLYR, which were 41 %, 38.0 %, and 38.0 % lower than CK, respectively. In addition, climatic and edaphic variables were the main contributors to GHG and NH₃ emissions. In conclusion, it is appropriate to promote the use of PM in the MLYR and SC regions, because of the ability to increase yields while reducing environmental impacts (lower GHGI and NH₃ emissions). The findings provide a theoretical basis for sustainable agricultural production of PM potatoes.

Keywords: Ammonia emissions; Biogeochemical modeling; Environmental impact factors; Global warming potential; Plastic film mulching; Potato yield.