Management strategies for reduced N2O emissions from North European agricultural soils

Time: 9 September, 2014
Place: Falkenberg, Sweden

Mitigation of nitrous oxide (N2O) emissions from agricultural soils is a major concern in order to limit agriculture’s contribution to climate change. In Northern European conditions in particular, climate itself constitutes a major challenge through long non-vegetated periods, frost-thaw cycles, wide occurrence of peat soils and excess soil water. The seminar dealt with N2O emissions from agricultural soils, with the focus on emissions related to management practices and mitigation strategies on the farm. An important aim was to present current research and knowledge within this topic and to increase the connection between research and advisors within agriculture. The NJF seminar was coordinated with a workshop for researchers and Swedish advisors on the following day, to which the participants and speakers at the seminar were invited.

The programme consisted of presentations by invited speakers from Norway, Denmark, Finland and Sweden. All participants were invited to bring a poster and to give a short oral presentation of its content. There were 30 participants (22 from Sweden, 4 from Norway, 1 from Finland, 2 from Denmark and 1 from Latvia). Five posters were presented.

The seminar started by presenting research on the microbial processes involved in N2O formation in the soil, microbial communities and factors affecting enzyme activities. Then experiences from the Nordic countries about how management practices (drainage conditions, tillage systems, crop rotations, slurry application etc.) affect N2O emissions were presented. There were also presentations about the IPCC emission factors, model development and use in advisory services, organic soils, different methods for detecting N2O flows in the soil, the ongoing research programme N2ORA and scenario calculations for reduction targets.

It was concluded that even though N2O formation and emissions from the soil largely depend on site-specific soil conditions and microbial communities, there are key drivers closely connected with management practices, e.g. demand and supply of nitrogen and oxygen in the soil. There is a clear win-win situation with respect to high N use efficiency by crops and related soil N depletion, and low risk of emissions. Moreover, measures for improving soil structure and drainage conditions represent win-win situations for crop production and low N2O emissions. Several studies have shown that incorporation of crop biomass or manure commonly results in emission peaks and there were a lot of discussions about strategies for reducing this risk and possible mismatches between different environmental impacts and production. For evaluation of total effects on GHG emissions, there was consensus about the importance of including indirect reductions or increases of emissions relating not only to N2O, but also gases such as methane and ammonia. A holistic perspective is needed for best management practices with respect to N use efficiency and climate impact, especially for systems with animal manure.