Greenhouse gas emissions from vegetables production in China

The Chinese vegetable production system is characterized by high fertilizer inputs and environmental risks. However, the spatial patterns and mitigation potential of greenhouse gas emissions from the Chinese vegetable production systems are unknown. In this study, greenhouse gas emissions and intensity in the Chinese vegetable production systems were quantified via life cycle assessment. The weighted average greenhouse gas emissions and intensity for Chinese vegetable production were 6,244 kg CO2-eq ha(-1) and 116 kg CO2-eq t(-1), respectively. The total greenhouse gas emissions were 139 Mt CO2-eq. N fertilizer was the largest contributor, accounting for 78.2 % of greenhouse gas emissions. Large variations in greenhouse gas emissions and intensity were detected among the regions as well as cultivation methods. Greenhouse gas emissions in the North region were 9.7-30.0 % greater than those in the South region due to 18.2-58.2 % higher N fertilizer rate in the North region. Greenhouse gas emissions from greenhouse vegetable production were 55.4-84.1 % greater than those from open-field vegetable production because the former had 13.0-51.3 % higher N fertilizer rate and more material structure input. Greenhouse gas intensity for greenhouse vegetable production was 39.6 % higher than that for open-field vegetable production in the North region. In contrast, greenhouse gas intensity was similar for both greenhouse and open-field vegetable production in the South region. The mitigation potential for greenhouse gas emissions on a per-hectare basis was higher for the North region than that for the South region, which was attributed to a relatively greater N fertilizer reduction potential in the North region. Optimizing the N rate could reduce the total greenhouse gas emissions from the Chinese vegetable production systems by 16.7 %. This work could enable researchers and policymakers to reduce the contribution of vegetable production to global climate change.