Comparing N2O fluxes from recently created extensive grasslands and sites remaining under intensive agricultural management

Abstract

The creation of extensive grasslands is encouraged under the current European Union Common Agricultural Policy (CAP), with the aim of enhancing the provision of ecosystem services, including the reduction of greenhouse gas (GHG) emissions. Nitrous oxide (N2O) is a potent GHG strongly associated with the use of nitrogen (N) fertiliser application in agriculture, but soil conditions (temperature and moisture) are also considered to be important drivers of N2O fluxes. Management strategies to reduce N2O emissions are urgently required to inform the sustainable agricultural practice. N2O fluxes from recently created (<10 years) extensive grassland on former intensive arable land in South East Scotland and on former intensive grassland in South West England were compared with paired sites remaining under long-term intensive management. N2O fluxes, soil temperature (Ts), water filled pore space (WFPS) and available N were measured in a range of grassland soils over three years. N2O emissions were generally <50gNha−1day−1 under all types of management. Maximum emissions were not explained by changes in Ts or WFPS. Lower N2O emissions were not observed in the extensified grasslands compared to long-term intensively managed sites. These findings suggest that the extensification of grasslands may not reduce GHG emissions for at least 10 years following extensification. This enables cost-benefit analyses of agri-environment schemes promoting enhanced ecosystem service provision from recently established species-rich grasslands (SRG) to be made.