Contents lists available at ScienceDirect Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet Ammonia emissions from liquid manure storages are affected by anaerobic digestion and solid-liquid separation Hambaliou Baldé a , Andrew C. VanderZaag a, ⁎ , Stephen D. Burtt a , Claudia Wagner-Riddle b , Leigh Evans c , Robert Gordon d , Raymond L. Desjardins a , J. Douglas MacDonald e a Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada b School of Environmental Sciences, University of Guelph, Ontario, Canada c Golder and Associates, Ottawa, Ontario, Canada d Department of Geography & Environmental Studies, Wilfrid Laurier University, Waterloo, Ontario, Canada e Environment and Climate Change Canada, Gatineau, Quebec, Canada ARTICLE INFO Keywords: Ammonia emissions Manure storage Anaerobic digestion Solid-liquid separation ABSTRACT The effects of manure management practices on ammonia (NH 3 ) emissions were evaluated using a micro- meteorological technique at four contrasting dairy storage facilities: untreated raw manure slurry (RM), solid- liquid separation with storage of separated liquids (SL), anaerobic digestion of manure and off-farm materials (AD), and anaerobic digestion with solid-liquid separation and storage of the liquid fraction (ADL). Annual average NH 3 emissions per surface area were lowest for RM (2.7 g m -2 d -1 ), followed by SL (4.5 g m -2 d -1 ), AD (10.0 g m -2 d -1 ), and ADL (15.5 g m -2 d -1 ). Lower NH 3 emissions from the RM storage were partly due to the 30 cm thick surface crust which formed on the storage surface in summer (wood shavings was used as bedding). Greater surface crusting at the AD storage compared to the ADL storage was also likely the reason for higher emissions at the ADL storage. Relationships between NH 3 emissions, temperature, and wind-speed were ob- served at all sites but were strongest at sites with minimal crusting (SL, ADL) and weak at the RM storage with a crust cover. Total NH 3 emissions from each storage facility (kg y -1 ) did not simply track the differences in fluxes; rather, facilities with greater storage (RM, AD, ADL) had higher emissions than the facility with less storage (SL) due to removal of solids and more frequent field application. Overall, bedding material, manure processing, and storage management all have important effects on NH 3 emissions from manure storage. 1. Introduction Agriculture is the largest source of anthropogenic ammonia (NH 3 ) emissions in Canada and livestock and fertilizer account for over 90% (Carew, 2010). Ammonia is a toxic gas that contributes to poor air quality and environmental degradation. Atmospheric ammonia leads to the formation of fine particulates that contribute to respiratory and cardiovascular diseases (Bittman and Mikkelsen, 2009). In the United States, health costs associated with NH 3 emissions were estimated to be 36 billion in 2006 (Paulot and Jacob, 2013). In Canada, NH 3 is the only gaseous pollutant which has increased in recent years. NH 3 emissions in 2014 were 21% higher than in 1990 mainly due to increased agri- cultural fertilizer use and larger livestock populations (Environment and Climate Change Canada, 2016). Ammonia emissions from manure storage and land application reduce the fertilizer value of manure, which is detrimental for farm efficiency (Sommer et al., 2006). Strategies of NH 3 emission reduction are needed to meet interna- tional agreements including the Gothenburg Protocol (UNECE, 1999). Furthermore, management practices that mitigate greenhouse gas emissions must take into account the impact on NH 3 emissions to avoid pollution-swapping. Studies suggest that manure management practices including anaerobic digestion (AD), solid-liquid separation (SLS) and AD combined with SLS could be effective to mitigate greenhouse gas emissions and provide extra economic benefits to farmers, but these technologies could increase NH 3 emissions from storage (Aguerre et al., 2012; VanderZaag et al., 2015; Holly et al., 2017). Anaerobic digestion of manure produces renewable energy from biogas and reduces methane emissions during digestate storage. Digestion also improves the nutrient availability in digestate (Karim et al., 2005). However, anaerobic digestion alone is not a viable miti- gation strategy for NH 3 emissions. Digestate has high levels of ammo- niacal nitrogen (TAN = NH 3 + NH 4 + ) and a higher pH than raw https://doi.org/10.1016/j.agrformet.2018.01.036 Received 16 July 2017; Received in revised form 18 November 2017; Accepted 26 January 2018 ⁎ Corresponding author at: Agriculture and Agri-Food Canada, K.W. Neatby Bldg., C.E.F., 960 Carling Ave., Ottawa, Ontario, K1A 0C6, Canada. E-mail address: Andrew.VanderZaag@agr.gc.ca (A.C. VanderZaag). Abbreviations: NH 3 , ammonia; AD, anaerobic digestion; ADL, anaerobically digested liquid fraction; RM, manure slurry; SL, separated liquid Agricultural and Forest Meteorology xxx (xxxx) xxx–xxx 0168-1923/ © 2018 Published by Elsevier B.V. Please cite this article as: Baldé, H., Agricultural and Forest Meteorology (2018), https://doi.org/10.1016/j.agrformet.2018.01.036