Abstract: A four-dynamic-chamber system was constructed to measure NOx and
NH_3 surface-exchange between a typical wheat field and the
atmosphere in the Yangtze Delta, China. The average fluxes of NO,
NO_2 and NH_3 were 79, −5.6 and
−5.1 ngN/(m^2·s), and 91, −1.8 and 23
ngN/(m^2·s), respectively for the wheat field and the
bare soil. The NO flux was positively correlated with soil temperature and the
fluxes of NO_2 and NH_3 were negatively
correlated with their ambient concentrations during the investigated period.
The compensation point of NO_2 between the wheat field and
the atmosphere was 11.9 μg/m^3. The emissions of NO-N and
NH_3-N from the urea applied to the wheat field were 2.3%
and 0.2%, respectively, which indicated that the main pathway of N loss from
the investigated winter wheat field was NO. Application of a mixture of urea
and lignin increased the emissions of NO, but also greatly increased the yield
of the winter wheat.