Algorithms Determining Ammonia Emission from Buildings Housing Cattle and Pigs and from Manure Stores

Livestock excreta and manure stored in housing, in manure stores, in beef feedlots, or cattle hardstandings are the most important sources of ammonia (NH 3 ) in the atmosphere. There is a need to quantify the emission, to assess the effect of emission on NH 3 and ammonium ( NH 4 + ) deposition to ecosystems and on the health risks posed by NH 4 + ‐based particles in the air. To obtain a reliable estimate of the emission from these sources, the processes involved in the transfer of NH 3 from the manure to the free atmosphere have to be described precisely. A detailed knowledge of the processes of NH 3 transfer from the manure and transport to the free atmosphere will contribute to development of techniques and housing designs that will contribute to the reduction of NH 3 emission to the atmosphere. For this reason, this review presents the processes and algorithms involved in NH 3 emission from livestock manure in livestock buildings and manure stores for pigs and cattle. Emission from poultry buildings and following land application of manure, although significant sources of NH 3 , have been reported in earlier reviews and are not included here. A clear description of the features that contribute to the total NH 3 emission from buildings will include information on stock class, diet and excreta composition, the distribution of emitting surfaces and knowledge of their mass transfer characteristics in relation to the building as a whole, as well as environmental variables. Other relevant information includes the quantity and composition of excreta produced by different classes of livestock and the influence of feeding regime; the influence of environmental variables on the production of NH 3 from excreta; how excreta is distributed and managed in livestock buildings; and factors that affect mass transfer of NH 3 in the building to the atmosphere outside. A major factor is the pH of the manure. There is a great need for algorithms that can predict pH as affected by feeding and management. This chapter brings together published estimates of NH 3 emissions and abatement techniques, and relates these to the factors listed above (excreta, NH 3 production, building, and mass transfer).