Effects of N Fertilizer Application Rates on N2O Emissions from a Vegetable Field in Wuhan, China - A Lysimeter Study

Nitrous oxide (N₂O) emissions from a typical vegetable cropping system in Wuhan, central China were measured from April 2007 to September 2008 on undisturbed soil monolith lysimeters using the closed chamber method. N₂O emissions showed an immediate and pronounced increase to additions of N fertilizer. Peak N₂O emissions were 42.5, 68.8, 548, 386 and 868 μg N m^-2 h^-1 in the N₀, N₁, N₂, N₃ and N₄ treatments, respectively. 65.2-77.0% of the total N₂O emissions were produced between April and September. Total N₂O emissions ranged from 1.4 to 25.6 kg N ha^-1 in the five treatments and the emission factor of the N₁, N₃ and N₄ treatment varied from 0.30% to 2.05%, and that for N₂ was 1.84-3.59%. There was a significant exponential relationship between the N application rate and total N₂O emissions, and the soil temperature was highly correlated to the N₂O emissions. The results also indicate that emissions from vegetable fields are a potential source of national N₂O flux in China.