Quantitative Relationship Between Nitrous Oxide Emissions and Nitrogen Application Rate for a Typical Intensive Vegetable Cropping System in Southeastern China

To explore the mechanism underlying the relationship between nitrous oxide (N 2 O) emissions and different nitrogen (N) application rates, we conducted a 2‐year‐round field experiment comprising seven vegetable crop seasons by using static chamber‐gas chromatographic techniques in a continuously cultivated vegetable cropping system in Southeastern China. The results showed that N application significantly affected the N 2 O emissions. The cumulative N 2 O emissions amounted to 16.9 ± 1.9, 25.2 ± 2.2, 30.0 ± 1.9, 36.7 ± 1.5, and 48.1 ± 2.2 kg N ha −1  y −1 for the five N application rates at 0, 370, 740, 1110, 1480 kg N ha −1  y −1 , respectively. Both linear and exponential relationship was observed between cumulative N 2 O emissions and N application rates. The emission factors ranged from 1.8 ± 0.1 to 2.3 ± 0.6% and averaged 2.0 ± 0.3%. The treatment receiving 2/3 of the conventional N fertilizer amount led to the lowest yield‐scaled N 2 O emissions. Therefore, according to this study the recommended N application rate should be reduced by one‐third for N 2 O mitigation while enhancing vegetable production in Southeastern China.