Cultivating Salix Viminalis in Agricultural-Riparian Transition Areas to Mitigate Agriculturally Derived N2O Emissions from Potato Cropping Systems on Prince Edward Island

Cultivating shrub willow ( Salix viminalis ) in agricultural-riparian transition areas has been proposed as a strategy for mitigating elevated riparian nitrous oxide (N 2 O) emissions in agricultural regions. Nitrogen-based fertilizers are water soluble, enter riparian areas through surface runoff and subsurface lateral flow, and are converted to N 2 O by incomplete anaerobic denitrification. Salix buffer strips can intercept and recycle fertilizer nitrate (NO 3 − ) into their biomass and/or promote complete denitrification, reducing N 2 O emissions. We investigated the impact of Salix viminalis buffers on N 2 O emissions relative to grassed buffers and upslope cultivated fields in potato rotations at 5 research sites across Prince Edward Island (PEI), Canada. Greenhouse gas (N 2 O, CO 2 , CH 4 ) flux at the soil-atmosphere interface was measured using non-steady-state static chambers in 2018 and 2019. NO 3 − exposure, soil temperature, and soil moisture content were quantified. Agricultural-riparian Salix significantly reduced N 2 O emissions even when high NO 3 − inputs occurred and following precipitation events. Mean cumulative seasonal reductions of 1.32 kg N 2 O–N ha −1 (− 0.02 to 6.16 kg N 2 O–N ha −1 ) were observed in Salix relative to cultivated fields; however, they were not significantly different than grass. The mean cumulative average global warming potential of Salix was 613 kg CO 2 e ha −1 lower than cultivated fields, with reductions of up to 2918 kg CO 2 e ha −1 . Differences in N 2 O flux between vegetation types were the greatest influencing factor. No hot moments of N 2 O emission were observed in Salix following high rainfall events, which coincided with up to 95% decreases in N 2 O emissions in Salix relative to cultivated fields.