High concentrations of H₂S gas are a human and animal health hazard, and can increase the rate of corrosion in barn facilities. Metabolic inhibitors can decrease H₂S concentration, but they have not yet been tested in an open system, like a barn. This study isolated manure bacteria capable of metabolizing H₂S, and then conducted semi-pilot and room-scale evaluation. Two compounds, molybdate and nitrate, were found to reduce H₂S concentration. Nitrate is short acting, but molybdate can act for up to 6 months. Applying both 24-48 hours before activities that agitate manure is recommended. The study found application was financially feasible – with costs under 1% of total costs for a growth cycle.