Ammonia emissions from the field application of liquid dairy manure after anaerobic digestion or mechanical separation in Ontario, Canada
Citation
Evans, L., VanderZaag, A.C., Sokolov, V., Baldé, H., MacDonald, D., Wagner-Riddle, C., Gordon, R. (2018). Ammonia emissions from the field application of liquid dairy manure after anaerobic digestion or mechanical separation in Ontario, Canada. Agricultural and Forest Meteorology, [online] 258 89-95. http://dx.doi.org/10.1016/j.agrformet.2018.02.017
Plain language summary
Anaerobic digestion (AD) and solid-liquid separation (SLS) are two strategies used to treat manure on farms. The treatments cause significant changes in many of the manure's characteristics. These characteristics can affect ammonia (NH3) emissions when the manure is applied to the field. Emissions from the application of manure were measured using wind tunnels to compare emissions from both treatments. The highest emissions were recorded during the spring application from the manure treated by AD. If these emissions are scaled by the total ammonia nitrogen (TAN), there is no significant difference between the AD and SLS treatments in either fall or spring. These results suggest that if farmers choose their application rates based on the TAN content in manure, the NH3 emissions from AD manure can be minimized. These results were also compared to the Ammonia Loss from Field Applied Manure (ALFAM) model which showed a general overestimate for NH3 emissions during the first 24 hours after application and an underestimate for emissions from day 2 to 22.
Abstract
Anaerobic digestion (AD) and solid-liquid separation (SLS) are manure treatment strategies used on dairy farms. These treatments change manure characteristics, such as pH, dry matter, and total ammoniacal nitrogen (TAN) which affect ammonia (NH3) emissions after field application. This study used eight wind tunnels (1 m2 each) to compare the effects of application season and dairy manure treatment (AD vs SLS) on NH3 emissions. The highest cumulative NH3 emissions were seen in the spring from the AD manure treatment, which had higher TAN and pH compared to SLS. On the other hand, when normalized by TAN application rate there was no significant difference between AD and SLS manure in either spring (52 and 54% of TAN after 22 d, respectively) or fall (26% and 27% of TAN after 15 d, respectively). This suggests that if farmers adjusted application rates based on TAN content, NH3 emissions from applied AD manure could be minimized. Results were compared to the Ammonia Loss from Field Applied Manure (ALFAM) model. The model characterized the temporal pattern of emissions reasonably well in spring, but not fall. The model generally overestimated NH3 emissions during the first 24 h after application, and underestimated emissions after incorporation from day 2 to 22.