Ammonia and greenhouse gas emissions from beef feedlot surface material treated with aluminum sulfate (alum) or microbial amendments

Authors: Spiehs, Mindy; Woodbury, Bryan

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2023
Publication Date: 12/19/2023
Citation: Spiehs, M.J., Woodbury, B.L. 2023. Ammonia and greenhouse gas emissions from beef feedlot surface material treated with aluminum sulfate (alum) or microbial amendments. Journal of Environmental Quality. 53(1):1-11. https://doi.org/10.1002/jeq2.20533.
DOI: https://doi.org/10.1002/jeq2.20533

Interpretive Summary: Livestock producers are facing increasing pressure to reduce ammonia and greenhouse gas emissions from their operations. Ammonia emitted from cattle feedlot operations produces unpleasant odors, can be harmful to humans and animals, and is a precursor to nitrous oxide, which, along with carbon dioxide and methane, contributes towards climate change. Livestock producers can reduce these emissions by applying products to the feedlot surface that can prevent the release of these gases into the air. Aluminum sulfate, known commonly as alum, is an amendment that has been used as a litter amendment in the poultry industry for almost 20 years. Another amendment is microbial products that contain a mixture of enzymes and bacteria to break down manure solids and promote the growth of beneficial bacteria. This study was designed to see if a microbial product or alum could reduce ammonia emissions and greenhouse gases from beef cattle feedlot surfaces. Ammonia, nitrous oxide, and methane were lower from feedlot surface material with amendments compared to the feedlot surface material that was left untreated. Emissions from feedlot surface material that received the microbial treatment were lower than the feedlot surface treated with alum. Methane emissions were similar for the untreated and alum-treated feedlot surface material but lower for the feedlot surface material that was treated with the microbial product. The results indicate that both alum and microbial amendments could be effective tools for producers to use to reduce emissions from the beef feedlot surface, with the microbial product providing additional reductions in emissions compared to the alum.

Technical Abstract: A lab-scale study evaluated ammonia (NH3) and greenhouse gases (GHG), emissions when aluminum sulfate (alum) or a microbial product were added to beef feedlot surface material (FSM). Three kg of FMS and 1.5 kg of water were added to stainless steel pans (50 cm x 30 cm x 6.5 cm). Treatments included a control (no amendment), 450 g alum, or 0.5 g microbial product. The pans were placed in an environmental chamber that was maintained at 23 °C and 50-60% humidity. Emissions were measured three times weekly for three weeks. Ammonia, N2O, and CH4 were lower (p < 0.01) from pans with amendments compared to the control pans; emissions from the FSM that received the microbial treatment was lower than the FSM treated with alum. Methane emissions were similar for the control and alum-treated FSM but lower (p < 0.01) for the FSM that was treated with the microbial product. Nitrate-N was lower and NH4+-N and total sulfur concentrations were higher in FSM treated with alum compared to no treatment or the microbial treatment (p < 0.01). Results indicate that both alum and microbial amendments have benefits in reducing emissions from the feedlot surface, with the microbial product providing additional reductions in emissions compared to the alum.