Nitrous oxide emissions from perennial grass cropping systems on a boreal mineral soil

Agriculture is the main anthropogenic source of nitrous oxide (N2O). Cultivation of perennial crops is a potential way to reduce N2O emissions. We quantified multi-year N2O emissions from two perennial cropping systems, reed canary grass (RCG) and a mixture of timothy and meadow fescue (TIM), on a boreal mineral soil. Mean annual emissions from TIM and RCG were rather similar, 600 mg N2O m–2 yr–1 and 670 mg N2O m–2 yr–1, respectively. Compared to the median N2O emissions from cropping systems in mineral soils in northern Europe (230 mg N2O m–2 yr–1), those in this study (720 mg N2O m–2 yr–1) were higher. The higher annual emissions and the observed decrease in annual emissions in our study with time was likely associated with the use of organic fertilizer during the pre-trial period.