[Greenhouse Gas Emission Characteristics and Influencing Factors from Vegetable Fields with Different Organic...

To clarify the characteristics of greenhouse gas emissions （CO₂, CH₄, and N₂O） and the comprehensive greenhouse effect from vegetable fields with different organic planting years, the differences in greenhouse gas emission flux, emission intensity （GHGI）, and global warming potential （GWP） and their influencing factors among vegetable fields with different organic planting years in Songhuaba, including 10 years, 6 years, 3 years, and conventional planting, were analyzed. The results showed that the CO₂ emissions from organic planting treatments were higher than those from conventional planting, whereas the N₂O and CH₄ emissions were the opposite. Compared to those from conventional planting, the CO₂ emission fluxes and cumulative emissions from organic cultivation for 10, 6, and 3 years increased by 121.28% and 40.44%, 144.61% and 51.39%, and 130.10% and 41.77% （P < 0.05）, respectively, and the N₂O emission fluxes and cumulative emissions decreased by 26.08% and 186.03%, 9.6% and 3.55%, and 35.9% and 151.78%, respectively. The CH₄ emission flux was shown as follows： conventional planting > organic planting for 10 years > organic planting for 6 years > organic cultivation for 3 years, and the CH₄ emissions from cultivational planting and organic planting for 10 years were shown as "source," while the CH₄ emissions from organic planting for 6 years and 3 years were shown as "sink." Compared with those from conventional planting, the GWP and GHGI from organic planting for 10 years and 3 years were reduced by 40.57% and 61.43%, 43.83% and 57.98% （P < 0.05）, respectively. Organic planting slightly reduced the vegetable yield but significantly reduced GWP and GHGI （P < 0.05）. Soil temperature and humidity, SOC, and inorganic nitrogen were the key factors affecting the difference in greenhouse gas emissions between treatments. Organic planting significantly reduced greenhouse gas emissions from vegetable fields, and the differences in greenhouse gas emissions among different years of organic planting were closely related to soil organic carbon and inorganic nitrogen. The research results can provide a scientific basis for carbon sequestration, emission reduction, and the green development of organic vegetable production systems.