Reducing GHG Emissions from Livestock Digestates and Effluents

This study demonstrates that good practices in managing livestock effluents and digestates significantly reduce emissions of ammonia, methane, and nitrous oxide. Anaerobic digestion reduces greenhouse gas emissions by 58% compared to raw cattle slurry, while combining it with solid-liquid separation cuts emissions from the clarified digestate fraction by 71%. Despite higher ammonia emissions—94% greater than bovine slurry—due to elevated pH and nitrogen content, mitigation techniques like storage coverage, acidification, and precision spreading (e.g. band application) are effective. Carbon footprint for milk production dropped from 1.3 to 1.1 kgCO2-eq/kg and from 1.1 to 0.9 kgCO2-eq/kg on two farms, reflecting a 20% reduction. Biogas-derived electricity has a negative carbon impact, generating carbon credits. Findings highlight the role of anaerobic digestion and innovation in achieving substantial emissions reductions in livestock systems.