Abstract:
Purpose Nitrous oxide (N2O) and methane (CH4)
are some of the most important greenhouse gases in
the atmosphere of the 21st century. Vegetated riparian bufers are primarily implemented for their water
quality functions in agroecosystems. Their location
in agricultural landscapes allows them to intercept
and process pollutants from adjacent agricultural
land. They recycle organic matter, which increases
soil carbon (C), intercept nitrogen (N)-rich runof
from adjacent croplands, and are seasonally anoxic.
Thus processes producing environmentally harmful
gases including N2O and CH4 are promoted. Against this context, the study quantifed atmospheric losses
between a cropland and vegetated riparian bufers
that serve it.
Methods Environmental variables and simultaneous
N2O and CH4 emissions were measured for a 6-month
period in a replicated plot-scale facility comprising
maize (Zea mays L.). A static chamber was used to
measure gas emissions. The cropping was served by
three vegetated riparian bufers, namely: (i) grass
riparian bufer; (ii) willow riparian bufer and; (iii)
woodland riparian bufer, which were compared with
a no-bufer control.
Results The no-bufer control generated the largest cumulative N2O emissions of 18.9 kg ha−1
(95%
confdence interval: 0.5–63.6) whilst the maize crop
upslope generated the largest cumulative CH4 emissions (5.1±0.88 kg ha−1
). Soil N2O and CH4-based
global warming potential (GWP) were lower in
the willow (1223.5±362.0 and 134.7±74.0 kg
CO2-eq. ha−1 year−1
, respectively) and woodland
(1771.3±800.5 and 3.4±35.9 kg CO2-eq. ha−1
year−1
, respectively) riparian bufers.
Conclusions Our results suggest that in maize production and where no riparian bufer vegetation is
introduced for water quality purposes (no bufer control), atmospheric CH4 and N2O concerns may result.
