Accurate estimates of agricultural greenhouse gas emissions underpin national land use policy and subsequent targets, e.g. the recent UK target for net zero carbon emissions by 2050. However, modelling of terrestrial sources of nitrous oxide (N2O) using atmospheric concentrations reveals that the bottom up greenhouse gas inventory for UK N2O emissions is either missing a major source(s) or underestimating a source(s). Increasing frequencies of extreme weather, e.g. prolonged drought and flooding, disrupt soil carbon, nitrogen and hydrological cycles, affecting the production and emission of greenhouse gases from soils as they recover their aeration status (post flooding) and moisture status (post drought). Increased N2O emission from soils during and post extreme weather events may be responsible for this 'missing' N2O. Whilst much is already known about the magnitude of N2O emissions from soil, most experiments used to derive improved N2O emission factors for use in in national greenhouse gas inventories have been conducted in the absence of extreme weather. The Extreme-N2O project will test the hypotheses that i) extreme weather events exacerbate N2O production and emission from soil, and ii) extreme weather events contribute to the 'missing' N2O.