Reducing Greenhouse Gas Emissions from Livestock Effluents and Digestates

This study highlights the effectiveness of reducing emissions of ammonia, methane, and nitrous oxide in managing livestock effluents and digestates through the adoption of good practices. By implementing practices such as anaerobic digestion and solid-liquid separation, greenhouse gas emissions can be significantly reduced. Anaerobic digestion alone can lead to a 58% reduction in greenhouse gas emissions compared to using cattle slurry. When combined with solid-liquid separation, emissions from the clarified fraction of digestate can be reduced by 71%. However, due to factors like high ammonia nitrogen content, higher pH, and lower ability to form surface crust, digestate may experience greater ammonia losses compared to bovine slurry. To mitigate this, techniques such as storage coverage, digestate acidification, and innovative spreading methods are recommended. The carbon footprint of milk production was notably decreased on farms implementing these practices, with a reduction from 1.3 to 1.1 kgCO2-eq/kg of milk for one farm and from 1.1 to 0.9 kgCO2-eq/kg of milk for another. This reduction in carbon footprint by approximately 20% showcases the significance of anaerobic digestion in mitigating greenhouse gas emissions. Furthermore, the electricity generated by biogas plants not only has a neutral impact but also allows for carbon credits. These findings emphasize the importance and effectiveness of sustainable practices in reducing emissions and improving environmental sustainability in livestock management.