Use of aluminum chloride to reduce ammonia and greenhouse gas emissions from beef pen surface material

Authors: Spiehs, Mindy; Stromer, Bobbi

Submitted to: Journal of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2026
Publication Date: 6/1/2026
Citation: Spiehs, M.J., Stromer, B.S. 2026. Use of aluminum chloride to reduce ammonia and greenhouse gas emissions from beef pen surface material. Journal of the ASABE. 69(3):367-378. https://doi.org/10.13031/ja.16554.
DOI: https://doi.org/10.13031/ja.16554

Interpretive Summary: The manure generated in a beef feedlot can be an important source of nutrients to fertilize agricultural cropland. However, if not managed properly, the nutrients from manure can escape into the environment through runoff or emissions as ammonia, nitrous oxide, carbon dioxide, and methane. Pen surface amendments are chemicals that can be applied to beef feedlot pens to trap and retain nutrients in the manure to prevent them from escaping as emissions into the atmosphere. Aluminum sulfate, often called alum, is one such amendment. Past studies have demonstrated that alum reduces ammonia emissions by lowering the pH of the pen surface material to prevent the volatilization of ammonia. However, the sulfur in alum reacts with pen surface material to create hydrogen sulfide, which is an odorous and sometimes dangerous gas. In this study, scientists evaluated the use of aluminum chloride to lower the pH of the pen surface material and trap nutrients without creating the negative hydrogen sulfide gas. Aluminum chloride was tested at rates of 0, 2.5, 5, and 10% of the mass of the pen surface material. The addition of aluminum chloride successfully lowered the pH of the pen surface material. As a result, cumulative emissions of ammonia, carbon dioxide, methane, and nitrous oxide were all reduced when aluminum chloride was added to the pen surface material, with additions of 5 or 10% aluminum chloride having the greatest reductions. Although total nitrogen retention in the pen surface material was not increased when aluminum chloride was used, there also was no increase in total sulfur, which is seen when alum is used as a pen surface amendment to lower pen surface material pH. Aluminum chloride is a promising option for beef feedlot producers to reduce feedlot odors.

Technical Abstract: Pen surface amendments are a tool that beef producers can use to reduce emissions and increase nutrient retention in manure. Previous studies demonstrated that aluminum sulfate (alum) could effectively lower ammonia (NH3) emissions but caused increased sulfide emissions. An alternative to alum is aluminum chloride (AlCl3). The objective of this study was to determine if the addition of AlCl3 to beef pen surface material (PSM) could lower NH3 losses while also lowering CO2, N2O and CH4 emissions. Aluminum chloride was added to pans containing 3 kg of PSM and 3 kg of water at a rate of 0, 2.5, 5, and 10% of the PSM mass and emissions were measured for 21 days. The addition of AlCl3 to PSM lowered (p < 0.01) the pH to 5.8 – 7.2 compared to untreated PSM (8.2). Nitrogen and sulfur content of the PSM was not affected by AlCl3 treatment (p >/= 0.14). Cumulative NH3 emissions decreased (p < 0.01) as AlCl3 inclusion increased and were 87.3, 60.5, 33.0, and 20.2 kg ha-1 for the 0%, 2.5%, 5%, and 10% AlCl3 treated PSM, respectively. Cumulative CO2, CH4, and N2O emissions also decreased linearly as the inclusion rate of AlCl3 increased. Aluminum chloride appears to be a promising option for beef feedlot producers to reduce emissions from the pen surface.