A review of methods for measuring emission rates of ammonia from livestock buildings and slurry or manure stores, part 1: Assessment of basic approaches

Ammonia emissions to the atmosphere are environmentally important, not only because of their role in the chemistry of air pollutants present in the atmosphere, but also because of the undesirable ecological effects of N compounds subsequently deposited from the atmosphere back to land. The great majority of ammonia emissions stem from livestock farming, and so there is an urgent need for improved methods for measuring emission rates of ammonia from livestock buildings and slurry or manure stores, e.g. to guide research on abatement strategies. In this paper, the possible approaches to this measurement task have been reviewed. Four basic approaches were identified: I-feed and manure nitrogen balance (ammonia by difference); II-summation of local ammonia sources; III-determining ammonia fluxes, either directly or indirectly, using an envelope more or less remote from the ammonia source; IV-measurement of ammonia sources to air e.g. by a tracer ratio method. An important objective of this review was to identify the best approach(es) for development to give a robust method for on-farm determination of ammonia emission rates. (Robust was defined basically as able to give an accurate result without an excessive level of operator skill.) A ranking exercise covering 11 aspects of each of the above approaches was carried out. Top rank was awarded to the measurement of ammonia sources to air (Approach IV), and second rank to one of the several possible embodiments of determining ammonia fluxes (Approach III). (C) 2000 Silsoe Research Institute.