Are There Potential Benefits From Using Microbial Products to Control Ammonia and Greenhouse Gases Released From Pig Slurry?

Livestock farming and its slurry management represent a significant contributor to global anthropogenic ammonia (NH₃) and greenhouse gas (GHG) emissions, resulting in negative impacts on the environment. The aim of this study was to evaluate the effect of two microbial slurry additives (A1, A2) on the emissions of NH₃, methane (CH₄) and carbon dioxide (CO₂) as well as on the changes in chemical properties of slurry in a mesocosm experiment. Two different controls (C1 and C2) were established, due to differences in the methodology of the additives studied. Although the A1 treatment showed significantly (3.3 times) higher NH₃ emissions than the A2 treatment, it is not evident that the additive alone is responsible for the observed differences, as (3.5 times) higher NH₃ emissions were also detected in the control C1 treatment than in the C2. An opposite trend was observed for CH₄ emissions, with higher average values in the A2 and C2 treatments. The differences can also be attributed to the different conditions in the use of the additive. Incubation of the A2 additive required additional water and maize grits, which diluted the slurry and changed its pH. The two additives had no impact on the emissions when compared to their respective control treatments. The results for CO₂ were more nuanced with no clear trends. The treatments had a significant effect on NH₃ emissions, whereas the weekly addition of pig slurry was the main contributing factor in the variation of CO₂ and CH₄ emissions.