Methane and nitrous oxide fluxes from a farmed Swedish Histosol

Summary Fluxes of the greenhouse gases methane (CH 4 ) and nitrous oxide (N 2 O) from histosolic soils (which account for approximately 10% of Swedish agricultural soils) supporting grassley and barley production in Sweden were measured over 3 years using static chambers. Emissions varied both over area and time. Methane was both produced and oxidized in the soil: fluxes were small, with an average emission of 0.12 g CH 4 m −2 year −1 at the grassley site and net uptake of −0.01 g CH 4 m −2 year −1 at the barley field. Methane emission was related to soil water, with more emission when wet. Nitrous oxide emissions varied, with peaks of emission after soil cultivation, ploughing and harrowing. On average, the grassley and barley field had emissions of 0.20 and 1.51 g N 2 O m −2 year −1 , respectively. We found no correlation between N 2 O and soil factors, but the greatest N 2 O emission was associated with the driest areas, with < 60% average water‐filled pore space. We suggest that the best management option to mitigate emissions is to keep the soil moderately wet with permanent grass production, which restricts N 2 O emissions whilst minimizing those of CH 4 .