Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: March 4, 2009
Publication Date: August 1, 2009
Citation: Cole, N.A., Mason, A., Todd, R.W., Parker, D.B. 2009. Effects of urine application on chemistry of feedlot pen surfaces [abstract]. Journal of Animal Science Supplement. 87:E-Suppl. 2, p. 148. Technical Abstract: Beef cattle feedlots can emit significant quantities of ammonia that may adversely affect air quality and decrease the fertilizer value of manure. The major source of ammonia loss may be urinary urea. We conducted three studies to evaluate the effects of urine on the chemistry of feedlot pen surfaces. In Experiment 1, samples were collected from the loose surface manure and the underlying layers (dry hard pack, wet hard pack, soil) of nine pens at each of three commercial feedyards. Samples were collected from an area that had recent (less than 10 minutes) urine deposition, and an area devoid of urine. The samples were analyzed for DM, ash, pH, electrical conductivity (EC), nitrate-N, ammonium-N, and total N, C, and P. The loose surface manure from urine spots had lower (P < 0.05) DM content (59.7 vs. 88.2%), higher (P < 0.05) pH (8.08 vs. 7.80), and greater (P < 0.05) EC (1.45 vs. 1.22 S/m), ammonium-N (6,755 vs. 2,381 ppm), total N (3.00 vs. 2.73%), and ammonium-N:total N (21.8 vs. 8.5%) than urine-free areas. In Experiment 2 (summer) and 3 (spring), 4 L of deionized water or artificial urine (21.4 g of urea/L) were applied to 1 m square plots (6/treatment) on a feedlot surface. The loose manure on the pen surface was sampled for 7 d and chemically analyzed. Compared to untreated plots, ammonium-N concentrations of plots treated with artificial urine increased (P < 0.001) from 391 to 6,343 ppm and the pH increased from 8.1 to 8.5 in less than 5 min following application and remained elevated (P < 0.05) for 79 to 96 h. Water applications caused a short term (2 to 4 h) increase in ammonium-N concentrations. These results support the hypothesis that ammonia losses from feedlot pens occur rapidly from urine spots. Therefore: 1) methods that do not take this into account will greatly underestimate ammonia emissions and 2) for optimal effectiveness, pen surface amendments to control ammonia losses must continuously be on the pen surface.