Winter N2O accumulation in sub-boreal grassland soil depends on clover and pH

Legumes such as clovers are included in grassland mixtures to improve nitrogen use efficiency. However, clover may fuel freeze-thaw N2O emissions, which are important in temperate to boreal regions. We investigated whether liming with dolomite mitigates this effect.

Previous lab studies have shown that raising pH lowers the N2O/N2 ratio of denitrification. Subsoil air probes, soil moisture and temperature loggers, and surface fastchamber flux estimates gave detailed data over winter in a liming trial in southeast Norway. Pure clover had the highest subsoil N2O accumulation during snow cover and prolonged anoxia. The pH effect was less clear.