A New Cost-Effective Method to Mitigate Ammonia Loss from Intensive Cattle Feedlot: Application of Lignite.

Concentrated animal feeding operations produce vast quantities of ammonia (NH₃). In open beef feedlot systems, 50-70% diet N is lost as NH₃. Currently there are no cost-effective measures to mitigate such losses. In this paper, we report an effective and economically-viable method to mitigate NH₃ emissions by the application of lignite. Lignite has chemical and physical properties to reduce NH₃ emissions from alkaline, high nitrogen-content animal excreta. We constructed two pens (20 × 20 m) to compare the effectiveness of lignite in reducing NH₃ emissions. Twenty-four steers were fed with identical commercial rations in each pen. The treatment pen surface was dressed with 4.5 kg m^-2 lignite dry mass whereas no lignite was applied in the control pen. We measured volatilised NH₃ concentrations continuously for 40 days using Ecotech EC9842 NH₃ analysers in conjunction with a mass balance method to calculate NH₃ fluxes. Our results suggest that lignite reduces NH₃ loss from the pen by up to 66%. The accumulative NH₃ losses were 6.3 and 2.1 kg N hd^-1 in the control and lignite treatment, respectively. Based on the estimated cost of lignite application, we suggest that lignite application is a cost-effective method to reduce NH₃loss from cattle feedlots.