LAUSR

Winter housing of dairy cows and beef cattle is common practise in north-western European countries such as the UK and Ireland. In cattle housing, urine and dung are deposited over a large floor surface area from which ammonia (NH3) emissions may rapidly occur. The application of additives to this emitting layer has the potential to significantly reduce NH3 volatilisation from cattle housing surfaces. A dynamic flow-through chamber based study was carried out to determine the NH3 abatement potential of 10 additives applied to dairy cow slurry covered concrete surfaces under simulated northwest European winter housing conditions. Peak NH3 fluxes for control (slurry only) treatments occurred at approximately 3–5 h post slurry application, peaking at 133 mg [NH3–N] m−2 h−1. Acidifiers offered the most potential for cost-effectively abating NH3 emissions from slurry-fouled surfaces by increasing the NH4+:NH3 ratio. Experimental data suggests that targeting a slurry pH of 6 at the housing floor stage can significantly reduce NH3 emissions from fresh excreta. Of the tested additives, alum was the most successful at abating NH3 emissions from slurry; particularly after 6 h (76% NH3 abatement), where the efficacy of alum was greatest relative to the other acidifiers. Alum was followed by calcium chloride (69%) and sulphuric acid (41%). Actisan, a commercially available bedding disinfectant was another successful NH3 abatement option (59% after 6 h). Caution is needed in extrapolating results from this chamber-scale study to cow house scale as spatial and temporal variability of excreta deposition and climatic factors create additional complexity.