Using aluminum sulfate or microbial feedlot surface amendments to reduce odor and gas emissions

Authors: Spiehs, Mindy; Woodbury, Bryan

Submitted to: Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE)
Publication Type: Proceedings
Publication Acceptance Date: 3/17/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: Two products were tested to see if they could reduce the emissions of greenhouse gases or odorous compounds like volatile organic compounds and ammonia from beef feedlot surfaces. Measurements were collected from feedlot surface material that contained no treatment (control), aluminum sulfate, or a microbial product. The aluminum sulfate was hypothesized to work by lowering the pH of the feedlot surface material to trap nitrogen in a form that can't be volatilized into the air as ammonia. The microbial product was hypothesized to work by altering the microbial community in the feedlot surface material to alter emissions. The microbial product reduced emissions of all three greenhouse gases and ammonia from the feedlot surface material compared to the control or aluminum sulfate-treated feedlot surface material. The feedlot surface material treated with the aluminum sulfate product resulted in less emissions of two of the greenhouse gases and ammonia compared to the untreated feedlot surface material. The results of the study indicate that aluminum sulfate and the microbial product may be helpful in reducing emissions from beef feedlots.

Technical Abstract: A lab-scale study was conducted to determine if ammonia (NH3), greenhouse gas (GHG), or odorous volatile organic compound (VOC) emissions were affected by the addition of aluminum sulfate (alum) or a microbial product to beef feedlot surface material (FSM). Six kg of FSM and 3000 g of water were added to stainless steel pans (50 cm x 30 cm x 6.5 cm). Treatments included a control (no amendment), 600 g alum, or 1.0 g microbial product. The total mass of each pan was recorded, and the pans were placed in an environmental chamber that was maintained at 23 °C and 50-60% humidity. Evaporative water loss was recorded daily, and soil moisture maintained by adding water to the pan weekly to account for the evaporative loss. Emissions were measured three times weekly for three weeks. Ammonia, N2O, and CH4 were lower (P < 0.01) from pans that received the amendments compared to the control pans; emissions from the FSM that received the microbial treatment was also 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. There were no differences in the odorous VOC emissions between treated and untreated FSM. The results of this study 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.