Effect of a lignite-coal extract on nutrient composition and gas emissions from cattle feedlot manure

Abstract

. 2007. Effect of a lignite-coal extract on nutrient composition and gas emissions from cattle feedlot manure. Can. J. Soil Sci. 87: 281-290. An experiment was conducted to determine the effect of a liquid lignite coal extract (LC; pH = 3.5) on gas emissions and the chemical composition of feedlot cattle manure. Eighty steers were randomly divided into four groups, penned individually, and fed a barley grain -barley silage diet sprayed with 0 (control), 0.5, 1.0 or 2.0 L of LC per tonne of dry matter. Manure samples (mixture of excreta and wood chips) were collected after 25, 53, 81, 109 and 150 d of including the LC in the diet. Inclusion of LC in the diet reduced both the pH and dissolved NH 3 + NH 4 + content of manure collected on days 25 and 53. Ammonia emissions were also significantly reduced on these occasions. In addition, butyric acid content was higher and isovaleric acid content lower in manure from cattle fed LC compared with manure from control cattle. Levels of nitrate, total volatile fatty acid (VFA), acetic, isobutyric, propionic, and capric acid in manure were not altered by the inclusion of LC in the diet. Greenhouse gas emissions (CO 2 , CH 4 and N 2 O) from manure were not affected by inclusion of LC in the diet. The lower manure pH, NH 3 + NH 4 + content and NH 3 emission at early sampling dates suggest that LC could play a role in reducing gaseous ammonia N emission to the atmosphere. Further studies are needed to determine whether the reduction in dissolved NH 3 + NH 4 + content in manure is due to an LC-mediated change in the amount of urea produced by the animals or to the inhibition of the hydrolysis of urea in manure. + et des émissions de NH 3 observée au début de l'expérience laisse croire que la lignite pourrait intervenir en diminuant les dégagements de N ammoniacal gazeux dans l'atmosphère. Il faudrait toutefois entreprendre d'autres recherches pour établir si la baisse de la concentration de NH 3 +NH 4 + dissous dans le fumier résulte d'une modification de la quantité d'urée produite par les animaux consécutivement à l'absorption de la lignite ou d'une inhibition de l'hydrolyse de l'urée dans le fumier. Mots clés:Bovins, parc d'élevage, urée, propriétés du fumier, teneur en acides gras volatils totaux, gaz à effet de serre, CH 4 , N 2 O, CO 2 , émissions, émissions d'ammoniacAs cattle feedlots continue to increase in size and density, so do the amounts of manure and odours associated with these industrial-scale operations. Manure, used for centuries as a fertilizer and soil conditioner, is now considered to be a pollutant and a liability in many places (Williams 1995). The general public has become increasingly concerned about the negative impact of large-scale feedlots on water and air quality and their implication for human health. These factors have driven the industry to seek new strategies to minimize nutrient flow and accumulation in the surrounding environment.