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Title: Ammonia emissions from feedlot surface of beef deep-bedded monoslope facilities

Author
item Spiehs, Mindy
item Woodbury, Bryan
item DORAN, BETH - Iowa State University
item Eigenberg, Roger
item KOHL, KRIS - Iowa State University

Submitted to: International Symposium on Air Quality and Waste Management for Agriculture
Publication Type: Proceedings
Publication Acceptance Date: 8/10/2010
Publication Date: 9/30/2010
Citation: Spiehs, M.J., Woodbury, B.L., Doran, B.E., Eigenberg, R.A., Kohl, K.D. 2010. Ammonia emissions from feedlot surface of beef deep-bedded monoslope facilities. In: Proceedings of the American Society of Agricultural and Biological Engineers. International Symposium on Air Quality and Manure Management for Agriculture. September 13-16, 2010, Dallas, Texas. 2010 CDROM.

Interpretive Summary: Deep-bedded confinement barns for beef cattle are becoming popular in the Upper Midwest. These barns are commonly bedded with crop residues. Research in the swine industry demonstrated that ammonia emissions were greater in deep-bedded barns compared to conventional confinement facilities. No research has been conducted on air emissions from deep-bedded cattle barns. This study was conducted to determine if there were particular areas within the pen that had high ammonia concentration, and to determine if environmental factors influenced the concentration of ammonia on the pen surface of deep-bedded barns. The results demonstrated that there was no consistent pattern of ammonia concentration within the pen. Areas of the pen with high ammonia concentration resulted from recent urination by the cattle. Ammonia concentration decreased rapidly after cattle were removed from the pen, with a majority of it being volatilized into the air within 4 hours of when cattle were removed from the pen. Ammonia concentration was highest when the ambient temperature was hot, compared to when cold or moderate temperatures were present. Depth of the bedded pack and pH of the bedded pack were poorly correlated to ammonia concentration. During the summer, producers using deep-bedded cattle confinement facilities may need to consider management changes to reduce ammonia emissions from their facilities.

Technical Abstract: The objectives of this study were to determine 1) spatial variability of steady-state ammonia concentration on the pen surface, 2) the effect of environmental factors on ammonia concentration, and 3) the nutrient composition and concentration of odorous compounds in manure from the pen surface of beef deep-bedded, monoslope facilities. Four pens (27.5 x 30.5 m) in two commercial beef deep-bedded, monoslope facilities were studied. In each pen, ammonia was collected in acid traps at 56 locations using 640 cm2 flux chambers. Moisture, pH, pack height, nutrient composition and concentration of odorous compounds were measured at each sample location. Ammonia samples were collected at 6-week intervals for 10 months, all other samples for 18 months. There was no consistent spatial pattern of ammonia concentration. Areas of high ammonia concentration resulted from recent urination of cattle. Ammonia concentration decreased rapidly after cattle were removed from pens, reaching an apparent baseline after 4 hours. Ammonia concentration increased as pack and ambient air temperature increased (P < 0.01) and was lower in the cold months compared to moderate and hot months (P < 0.01). Depth and pH of bedded pack were affected by seasonal changes but were poorly correlated to the ammonia concentration on the feedlot surface of monoslope facilities (R2 = 0.07). Concentration of total volatile fatty acids (VFA), straight-chain VFA, and branch-chain VFA in manure were highest in the cold and moderate months and lowest during the hot months. The concentration of aromatic compounds in the manure was not affected by season.