Impact of fertilization on ammonia volatilization and N₂O emissions in an open vegetable field

A field experiment with different nitrogen fertilization rates and mitigation measures was conducted in an open-ground vegetable field on the North China Plain to investigate the effects of nitrogen application level and management practices on ammonia volatilization and N₂O emission. Reducing the nitrogen fertilization rate by 20% and by 50% decreased ammonia volatilization by 25.7% and 48.0%, respectively, during the spring-sowed cucumber growth period. Amendment with combined inhibitors and biochar decreased ammonia volatilization loss by 10.0% and 6.1%, respectively. Reducing nitrogen fertilization rate by 20% and 50% decreased N₂O emission by 28.8% and 61.0% during the spring-sowed cucumber growth period. Addition of combined inhibitors decreased N₂O emission by 58.9%, while it was increased by 14.1% with biochar addition. Under the same application method of banding application, replacing 30% nitrogen fertili-zer with organic manure did not show any significant mitigation for ammonia volatilization and N₂O emission. For the intensively managed vegetable fields, reducing the nitrogen application rate appropriately was the most effective measure to reduce ammonia volatilization and N₂O emission.