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.