A Novel Approach To Estimate The Abatement Of Ammonia Emissions From Mitigation Techniques At Farm-Scale Slurry Stores Exemplified By A Semifloating Cover

Ammonia (NH3) losses from livestock slurry stores substantially contribute to agricultural emissions to the atmosphere. Gas release from slurry storage facilities is driven by interactions between store operations and meteorological conditions. This study quantifies the abating effect of an impermeable semifloating cover as an emission mitigation technique at a farm-scale slurry storage tank. Emissions were measured over 1 yr and compared with the preceding 2 yr of measurements with the uncovered tank. In this novel approach, emission data were aggregated to categories within 1 h measuring intervals according to five key factors influencing emissions (time span after agitation and tank-filling level as surrogates for natural crust occurrence; the meteorological parameters precipitation, air temperature, and wind speed) for the two consecutive measurement campaigns with and without the cover. The emission abatement effect of the cover was determined by emission modeling of the entire measuring campaign based on measuring intervals of the uncovered and the covered tank where the aggregated categories of influencing factors were equal. The resulting average emission abatement was 48%. An average abatement of 37 and 54% was achieved during periods with and without a surface crust, respectively. The emission reduction was less with low tank filling level due to higher air exchange through openings of the cover. The presented approach is applicable to evaluate emission mitigation techniques for single farm-scale stores. With adequate measurement duration, it is appropriate to produce reliable emission data reflecting the complex interactions between emissions and influencing factors occurring at real-world storage facilities.