Dynamic responses of nitrous oxide emission and nitrogen use efficiency to nitrogen and biochar amendment in an intensified vegetable field in southeastern China

Abstract

Abstract Intensive vegetable production exhibits contrasting characteristics of high nitrous oxide (N 2 O) emissions and low nitrogen use efficiency ( NUE ). In an effort to mitigate N 2 O emissions and improve NUE , a field experiment with nine consecutive vegetable crops was designed to study the combined effects of nitrogen (N) and biochar amendment and their interaction on soil properties, N 2 O emission and NUE in an intensified vegetable field in southeastern China. We found that N application significantly increased N 2 O emissions, N 2 O–N emission factors and yield‐scaled N 2 O emissions by 51–159%, 9–125% and 14–131%, respectively. Moreover, high N input significantly decreased N partial factor productivity ( PFPN ) and even yield during the seventh to ninth vegetable crops along with obvious soil degradation and mineral N accumulation. To the contrary, biochar amendment resulted in significant decreases in cumulative N 2 O emissions, N 2 O–N emission factor and yield‐scaled N 2 O emissions by 5–39%, 16–67% and 14–53%, respectively. In addition, biochar significantly increased yield, PFPN and apparent recovery of N ( ARN ). Although without obvious influence during the first to fourth vegetable crops, biochar amendment mitigated N 2 O emissions during the fifth to ninth vegetable crops. The relative effects of biochar amendments were reduced with increasing N application rate. Hence, while high N input produced adverse consequences such as mineral N accumulation and soil degradation in the vegetable field, biochar amendment can be a beneficial agricultural strategy to mitigate N 2 O emissions and improve NUE and soil quality in vegetable field.