Carbon dioxide and methane exchange of a perennial grassland on a boreal mineral soil

Cultivation of perennial crops can be an option to sequester carbon in agricultural soils. To determine the carbon budget of a perennial cropping system under the boreal climate, we studied carbon dioxide (CO2) and methane (CH4) exchange of timothy and meadow fescue mixture (TIM) on a boreal mineral soil. Based on the mean annual net ecosystem CO2 exchange (NEE), TIM was a sink for both CO2 (–1000 g CO2 m–2) and CH4 (–140 mg CH4 m–2). In comparison, soil without vegetation (BARE) was a source of CO2 (1300 g CO2 m–2). Based on the literature review, the net CO2 uptake of TIM was similar to the perennial cropping systems in northern Finland but higher than that of the annual cropping systems in this region. Our multi-year study shows that the perennial cultivation system based on TIM is an environmentally sustainable land-use option to mitigate agricultural CO2 emissions in regions with short growing seasons.