ammonia, acidification, slurry, storage, chemical amendment, greenhouse gases.
Emissions of greenhouse gas (GHG) and ammonia (NH3) from cattle and cow slurry storage can be minimised by acidification. A knowledge gap exists to find chemical amendments that are suitable and cost effective to mitigate both GHG and NH3 gases simultaneously. This study showed that ferric chloride, sulphuric acid, alum and acetic acid reduced NH3 by 96%, 85%, 82% and 73%, respectively. In terms of methane (CH4), ferric chloride, alum, sulphuric acid and acetic acid reduced emissions by 98%, 96%, 95% and 94%, respectively. Previous studies have found that the reduction of pH to below 6 can inhibit the release of these gases; however, the effectiveness can vary depending on each amendments composition. Considering the cost per tonne of amendment, N savings (based on fertiliser replacement value) and the reduction in GHG, the best performing amendment was alum. Currently, the cost of implementing these amendments is, at best, cost neutral. Therefore, incentivising chemical amendments for the abatement of GHG and NH3 gases from slurry storage is needed. This incubation experiment is an effective means of pre-screening amendments before they are explored at pilot- or full-scale with subsequent field application. Future research should consider assessment of cheaper on- and off-farm alternative waste streams as slurry amendment.