Novel slurry additive reduces gaseous emissions during storage thereby improving renewable energy and fertiliser potential
Camilla Thorn, Stephen Nolan, Chui Sang Lee, Ruairi Friel, Vincent O’Flaherty
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.