A study was conducted to investigate effects of feeding encapsulated nitrate (EN) to beef cattle on ammonia (NH3) and greenhouse gas emissions from their manure. Eight beef heifers were randomly assigned to diets containing 0 (control), 1, 2, or 3% EN (55% forage dry matter; EN replaced encapsulated urea in the control diet and therefore all diets were iso-nitrogenous) in a replicated 4 × 4 Latin square design. Urine and feces collected from individual animals were reconstituted into manure and incubated over 156 h using a steady-state flux chamber system to monitor NH3, methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) emissions. Urinary, fecal, and manure nitrate (NO3 -)-N concentration linearly increased (P < 0.001) with feeding EN, and urinary urea concentration tended to be lower (P = 0.078) for EN versus Control. The hourly emissions of NH3, CO2, and N2O (mg head-1 h-1) were not affected, although NH3 emission rates tended to be lower (P = 0.070) for EN compared with Control at 0 to 12 h. Cumulative NH3, CO2, and N2O emissions over 156 h were not affected, but CH4 emissions were less (4.5 vs. 7.4 g head-1; P = 0.027) for EN compared with Control. In conclusion, although NH3 emissions were initially lower for EN manures, total NH3 emitted over 156 h was not affected. Dietary EN lowered CH4 emissions from manure, and, despite greater NO3 - concentrations in EN manure, N2O emissions were not affected in this short-term incubation.
All Science Journal Classification (ASJC) codes
- Environmental Engineering
- Water Science and Technology
- Waste Management and Disposal
- Management, Monitoring, Policy and Law