This study aimed to quantify GHG emissions over two consecutive years (March 2007 to March 2009)
from a 30 year (lychee) orchard in the humid subtropical region of Australia. GHG fluxes were measured
using a combination of high temporal resolution automated sampling and manually sampled chambers.
No fertiliser was added to the plots during the 2007 measurement season. A split application of nitrogen
fertiliser (urea) was added at the rate of 265 kg N ha−1 during the autumn and spring of 2008. Emissions
of N2O were influenced by rainfall events and seasonal temperatures during 2007 and the fertilisation
events in 2008. Annual N2O emissions from the lychee canopy increased from 1.7 kg N2O–N ha−1 yr−1
for 2007, to 7.6 kg N2O–N ha−1 yr−1 following fertiliser application in 2008. This represented an emission
factor of 1.56%, corrected for background emissions. The timing of the split application was found to
be critical to N2O emissions, with over twice as much lost following an application in spring (2.44%)
compared to autumn (EF: 1.10%). This research suggests that avoiding fertiliser application during the
hot and moist spring/summer period can reduce N2O losses without compromising yields.
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