Impact of Management Practices on Whole Farm Ammonia Emissions on Ontario Dairy Farms

Abstract

Agriculture is the largest source of anthropogenic ammonia emissions in Canada. Ammonia is not only a toxic gas but contributes to poor air quality and environmental degradation. A micrometeorological inverse dispersion technique was used to measure ammonia (NH3) at two dairy farms in Ontario, Canada. Study farms used solid-liquid separation while one farm stored anaerobically digested liquid manure and the other untreated liquid manure. Measurement campaigns were conducted seasonally and were designed to partition sources (e.g. barns, manure storages) within the operation as well as measure emissions from the whole operation. Field application trials using 1m2 wind tunnels were also done to compare NH3 emissions after field application of manures from both farms. Analyses of manure showed that anaerobic digestion and separation of dairy manure does increase the pH and ammonium content over separation alone. Results showed that NH3 emissions from dairy farms employing anaerobic digestion are 60% higher than emissions from farms using only a solid-liquid separation system. Emissions from the field application of the two manures showed that on a per volume basis, AD manures do have higher emission rates, but that if scaled by total nitrogen applied there is no significant differences between the two manures. Overall, when the results are synthesized, it is shown that at the farm scale emissions from AD farms are significantly higher than from farms without AD technology. However, other farm management practices such as application timing, incorporation, storage duration and system design can have an equally significant impact and could be crucial to mitigating increased emissions from AD systems.