Environmental Impact Of Beef Feedlot Cattle Feces, Urine, And Bedded Pack Facilities

Abstract

Throughout the Upper Midwest, farmers have observed an increase in land prices and fertilizer prices resulting in the increased popularity of confinement feeding facilities such as mono-slope and hoop barns with bedded packs. Environmental and public pressure has been placed on the agriculture community to improve NH3, GHG, and VOC emissions from CAFOs. A study was conducted to determine the effect of bedding material (corn stover (CS), bean stover (BS), wheat straw (WS) or pine wood chips (PC)) and environmental ambient temperature (15°C (COLD) or 30°C (HOT)) on concentration of NH3, CH4, CO2, N2O, H2S, and odorous VOCs in air samples collected in headspace above lab-scaled bedded packs over a 42-d study. Bedded packs were housed in a common area at 18°C through Week 3 before being placed at their treatment temperature in respective environmental chamber. A significant (P = 0.0422) interaction between bedding material, ambient temperature and age of bedded pack was observed for CH4. Methane flux was similar across all treatments at Week 4. As bedded packs aged all the bedded packs in the cold chambers and the packs with the HOT-BS, HOT-PC, and HOT-WS treatment produced similar yet minimal flux compared to HOT-CS at Week 5. Whereas, at Week 6 HOT-BS and HOT-CS had significantly greater flux (10.48 and 12.59 mg m-2 hr-1; respectively) across all other treatments. A significant two-way interaction for bedding material by ambient temperature for NH3, H2S, and CO2, and N2O flux was observed (P = 0.0094, P < 0.0001, and P = 0.0005; respectively). Ammonia flux from BS, CS, and WS bedding material treatments was significantly greater at HOT ambient temperatures than COLD. Across all treatments significantly (P = 0.0407) greater NH3 flux (372.9 mg/m2/hr) was observed in headspace of HOT-WS bedded packs. Across all treatments COLD-BS had significantly (P < 0.0001) greater H2S flux than any other treatment, while bedding materials at HOT temperatures were similar. Carbon dioxide flux from WS bedding material was significantly (P < 0.05) greater no matter ambient temperature and increase over time. A significant (P = 0.0357) two-way interaction between ambient temperature and age of bedded pack for H2S flux was observed. Bedded packs maintained in COLD environments has similar H2S flux across weeks, while HOT treatments significantly (P = 0.0098) decreased from Week 4 to 6. Total aromatic compounds had significant (P = 0.0455) interaction for bedding material by ambient temperature as HOT were significantly greater than COLD across all bedding material types. An ambient temperature by age of bedded pack and bedding material by ambient temperature significant (P = 0.0008 and P = 0.0083)); respectively) interaction existed for total sulfide compounds as flux from COLD increase and HOT decrease over time. Total sulfides were the largest from PC bedded pack regardless of the temperature. Significant interactions for ambient temperature by age of bedded pack and bedding material by age of bedded pack was observed for both total BCFA and total SCFA. Total BCFA and total SCFA flux from CS and WS was significantly (P < 0.05) greater at Week 4, while total BCFA and total SCFA flux from HOT bedded packs decreased significantly (P < 0.05) from Week 4 to 5. Total OAVs decreases over time for both HOT and COLD treatments, although COLD treatments had significantly (P < 0.05) lower total OAVs regardless of age of bedded pack. Bedding types BS and PC had the lowest total OAV across all weeks. Aromatic compounds generated 72.0% of the total OAV over time. Producers should evaluate their bedded pack management system and consider potential bedding material being used and bedded pack removal frequency based on seasonal ambient temperatures to reduce overall operation flux emissions.