Measuring nitrous oxide emissions from conventional and controlled release fertilisers in south-east Queensland pineapple production

Nitrous oxide (N₂O) is a potent greenhouse gas with a global warming potential 298 times higher than carbon dioxide. Soils are a natural source of N₂O, contributing 65% of global emissions. This paper is the first in Australia to measure and compare N₂O emissions from pre-plant controlled release (CR) and conventional granular (CV) fertilisers in pineapple production using static PVC chambers to capture N₂O emissions. Farm 1 cumulative emissions from the CR fertiliser were 3.22 kg ha^-1 compared to 6.09 kg ha^-1 produced by the CV. At farm 2 the CV blend emitted 2.36 kg ha^-1 in comparison to the CR blend of 2.92 kg ha^-1. Daily N₂O flux rates showed a relationship of direct response to rainfall and soil moisture availability. High emissions were observed for wheel tracks where increased N₂O emissions may be linked to soil compaction and waterlogging that creates anaerobic conditions after rain events. Emission measurements over three months highlighted the inconsistencies found in other studies relative to reducing emissions through controlled release nitrogen. More investigations are required to verify the benefits associated with controlled release fertiliser use in pineapples, placement and seasonal timing to address N₂O emissions in pineapples.