Novel slurry additive reduces gaseous emissions during storage thereby improving renewable energy and fertiliser potential

Abstract

Gaseous emissions from stored livestock manures and slurries are a significant source of greenhouse gases (GHG) and ammonia, accounting for more than 10% of all agricultural emissions in the US and EU. Nitrogen and carbon losses from these emissions reduce the utility of slurry as a fertiliser and as a feedstock for renewable energy generation. Slurry treatment technologies in the form of slurry additives represent an under-utilised means of reducing gaseous emissions and preserving the nutrient content of stored manures. A novel, reactive oxygen halide-based, temporal methanogenic inhibitor was tested on stored cattle slurry. Laboratory storage models were employed to replicate on-farm manure practices in a covered setting. Total gaseous emissions from slurry were reduced by up to 90% during storage. Different sources of reactive oxygen could be used to create a similar inhibition, where the breakdown products are not harmful to the environment or detrimental to the onward use of the slurry. Indeed, additive-treated slurry made a richer feedstock when anaerobically co-digested, increasing methane output by 17%. This proof of concept should now be assessed at farm-scale.