Ammonia and Greenhouse Gas Concentrations at Surfaces of Simulated Beef Cattle Bedded Manure Packs

Bedding is used in livestock operations to facilitate manure management and provide comfort for the animal. Our research objective was to determine differences in ammonia (NH 3 ), carbon dioxide (CO 2 ), nitrous oxide (N 2 O), and methane (CH 4 ) concentrations from simulated beef cattle bedded manure packs (BP) related to storage length (0 to 3, 3 to 6, and 6 to 9 weeks), bedding material (corn stover (CS) or soybean stubble (SB)), and temperature (10°C or 40°C). Bedding, fecal material, and urine were added weekly to 24 laboratory-scale BP (n = 2 per treatment combination). Static flux chamber samples from BP headspace were analyzed for CO 2 , N 2 O, and CH 4 at 0, 24, 46, and 144 h and for NH 3 at 0, 5, 9, 23, 34, 46, and 144 h after weekly manure and bedding addition for three consecutive weeks using a doubly repeated measures design. Ammonia concentrations were three times higher above BP in the Hot chamber (1190 ppm, SE = 47) compared to the Cold chamber (400 ppm, SE = 9). Average concentrations for CO 2 (6033 ppm, SE = 211), CH 4 (42 ppm, SE = 4), and N 2 O (0.61 ppm, SE = 0.05) were approximately twice as high at 40°C as for CO 2 (3902 ppm, SE = 161), CH 4 (21 ppm, SE = 2), and N 2 O (0.39 ppm, SE = 0.03) at 10°C. At 40°C, NH 3 concentrations above CS treatments (1388 ppm, SE = 75) were higher than above SB treatments (992 ppm, SE = 51). Overall, a higher storage temperature increased all gas concentrations. Increases in concentrations with length of storage were detected for CH 4 and CO 2 , while bedding affected NH 3 at 40°C and impacted changes in increase for CH 4 concentrations. These data suggest that seasonal management decisions can impact gas production and release in barns using BP. During hot months, NH 3 , CO 2 , CH 4 , and N 2 O concentrations are expected to increase and when applying CS as the bedding, NH 3 concentrations will likely be higher with CS bedding compared with SB bedding. At temperatures around 10°C, CO 2 and CH 4 concentrations are anticipated to increase with longer storage lengths.