Effect of Calcium Sulphate Dihydrate on GHG and Ammonia Emissions from Cattle Slurry during Storage

A significant part of ammonia (NH3), methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) are produced from the decomposition of slurry organic matter in livestock facilities during manure storage and treatment phases. Therefore, various strategies such as manure management practices, types of treatment and additives have been adopted in order to explore the nutrient losses from livestock manure and minimize the environmental impact due to NH3 and greenhouse gas (GHG) emissions. The aim of this study was to evaluate the effects of a commercial additive (calcium sulphate dihydrate) on slurry characteristics and N losses, and on NH3 and GHG emissions. Its environmental impact was assessed with a Life Cycle Assessment (LCA) methodology. Six barrels were filled with 65 litres of cattle slurry, among which three were used as the control, and three as the treatment. Gaseous emissions and slurry composition were studied over a 26-day storage period. The results indicated that the use of the additive led to a reduction of total nitrogen, nitrates as well as NH3 and GHG emissions. From the LCA results a higher environmental sustainability was achieved in the scenario with the additive compared to the scenario without it. In conclusion, the addition of calcium sulphate dihydrate has beneficial effects both on emission mitigations and on the environment. Moreover, the nitrogen present in the treated slurry makes it a valid substitute for a mineral fertilizer, which can be considered as an environmental credit.