Emerging options for mitigating N2O emissions from food production by manipulating the soil microbiota

Improved understanding of the microbes producing and reducing N2O spurs the invention of direct and manipulative methods to reduce N2O emissions, beyond that achieved by 'good agronomic practice'. A core issue is the kinetics of N2O-reductase by denitrifying organisms during anoxic/hypoxic spells; the 'hot moments' of N2O emission. Soil pH has a pervasive effect on the Expression of the enzyme, and liming soils will reduce the N2O emission. In this review we present some novel options for mitigation of N2O emissions, beside liming. During recent years, an increasing number of strongly N2O reducing organisms have been identified, and ways to enhance their numbers and activity in soil are emerging. One suggestion is to develop inoculants for legumes that are strong N2O reducers. Another is to grow N2O reducing organisms in digestates from biogas production. These promising options need further elaboration and validation.