Location: Livestock Bio-Systems
2025 Annual Report
Objectives
Objective 1: Develop pen surface amendments and treatment practices for concentrated animal feeding operations (CAFO) to reduce emissions to the environment, including greenhouse gases (GHG) and odors.
Sub-objective 1.A: Determine the effect of climatic conditions on GHG and odor emission from beef feedlot pen surfaces from various geographical locations.
Sub-objective 1.B: Evaluate the addition of feedlot surface amendment(s) in lab-scale studies to reduce emission of GHG and odorous compounds from beef feedlot pen surfaces from various geographical locations.
Sub-objective 1.C: Evaluate the validity of using electromagnetic induction surveys to predict and mitigate spatially variable feedlot surface GHG and odor emissions.
Sub-objective 1.D: Determine seasonal and annual ammonia transport and dry deposition from beef confinement facilities in and around the livestock facility.
Sub-objective 1.E: Determine NH3 and H2S emissions from swine finishing barns and manure storage based on feed inputs.
Sub-objective 1.F: Continue developing treatment methods for removing certain antimicrobials from wastewater and expand the efficacy of this process for additional pharmaceutically active compounds.
Objective 2: Quantify how long-term manure additions to soil alter soil health as measured by chemical, physical, and biological properties.
Approach
Concentrated animal feeding operations (CAFOs) cause environmental concerns because of the organic, inorganic, pathogenic, and pharmaceutical residues sometimes found in manure and their potential as sources for contamination of soil, surface and groundwater, and air quality. The multifaceted, integrated research proposed herein will provide valuable information for managing the impact of manure on the environment. This work focuses on beef and swine production with an emphasis at the pen because that is where manure is most concentrated, and where management can have a significant impact. A series of experiments are planned to better understand how emission characteristics vary based on climatic conditions and geographical location within the U.S. of open-lot beef pen surface material (PSM). Effects of spatial location within the pen will also be examined. It is anticipated this information will provide insight for the development of precision pen surface management practices for improved environmental control, including the use of pen surface amendments. Nitrogen deposition surrounding the beef feedlot, and the effect of dietary inputs on nitrogen (N) and sulfur (S) outputs from a swine facility will contribute towards larger efforts to model air emissions from livestock production facilities. Additional experiments will develop methods to remove antibiotics and other pharmaceutical compounds in beef, swine, and dairy wastewater prior to land application. The removal of antibiotics and other pharmaceutical compounds will mitigate the potential spread of antimicrobial resistance (AMR) in the environment. Finally, the impacts of manure application as a fertilizer amendment will be examined to better characterize the benefits for improving sustainability of soils for crop production. The unique resources and scientific expertise at the U.S. Meat Animal Research Center (USMARC) will enable successful completion of this plan.
Progress Report
Sub-objective 1A: Data has been analyzed to determine nitrogen (N) and carbon (C) losses from beef feedlot pen surface material following a precipitation event. Pen surface material from feedlots in the Southern Plains and in the Northern Plains were evaluated in a lab-scale setting with three simulated rain events over a 42-day period. There were no differences in the ammonia (NH3), nitrous oxide (N2O), or methane (CH4) flux from the pen surface material from either region. Carbon dioxide (CO2) loss was greater for the pen surface material from the Northern Plains. Carbon dioxide and N2O were influenced by moisture content of the pen surface material, with simulated rainfall events creating peaks when other variables such as temperature are held steady. Mitigations strategies for both regions would be best focused on intervention when rain events occur, especially in the more humid and wet Northern Plains region.
Sub-objective 1B: A preliminary study was conducted to determine if soldier fly larvae can be used to digest beef open-lot pen surface material. Pen surface material with two different moisture contents (70% and 50%) was measured for 14 days to determine N, C, and odor losses from the pen surface material. An automated sampling system was created to allow for continuous monitoring over the two-week sampling period. Additional studies are planned to start in August 2025 which will evaluate mixtures of beef cattle pen surface material and wastewater as a nutrient source for the fly larvae and to determine the C, N, and odorous losses when soldier fly larvae are used for digestion of beef cattle manure.
Lab-scale and on-farm studies have been conducted to evaluate the addition of feedlot surface amendments and animal diet on feedlot surface characteristics, odor, and gas emissions. Lab-scale experiments have been conducted to evaluate the effectiveness of microbial and chemical feedlot surface amendments in 42-day wet-dry cycles to determine how the two amendments reduce odorous NH3, N2O, CH4, and CO2 over time. A second study evaluated blended beef and chicken manure with considerations of soil properties and carbon and nitrogen losses to the atmosphere. An on-farm project began in June 2025 at a Clay Center, Nebraska, beef feedlot to evaluate the addition of a microbial additive added to the feedlot surface area. This study provides a third year of data for a project initiated in FY 2023. Air samples are being collected on seven occasions over an 18-day period and analyzed for NH3, CO2, N2O, and CH4. Manure nutrient content and pH are also being determined at the beginning and the end of the study. A second on-farm study was also initiated in June 2025 at a Clay Center, Nebraska, beef feedlot to evaluate the N and C losses from the feedlot pen surface to the atmosphere as NH3, CO2, N2O, and CH4 when two dietary supplements are fed to beef finishing cattle. The two on-farm projects will conclude in late July 2025.
Sub-objective 1C: To determine seasonal and annual NH3 transport and dry deposition from beef confinement facilities in and around the livestock facility, a meteorological station was erected, and twenty-five data collection points established in an array surrounding a 6,000-animal beef feedlot located near Clay Center, Nebraska. Data has been collected every other week since August 2023 and sent to the ARS facility in Lincoln, Nebraska, for NH3 analysis. Weather and ammonia data is sent to the U.S. Environmental Protection Agency for integration into their NH3 deposition model. Data collection using Ogawa passive NH3 samplers will continue through FY 2026. Plant tissue samples were also collected quarterly to determine nitrogen deposition onto plant tissue.
Sub-objective 1F: Hydrophobic diatomaceous earth was optimized for synthesis conditions and further characterized to better understand the surface properties. Additional work was also completed to show that the synthesis is reproducible and a cost analysis performed to determine the cost to synthesize the material in bulk.
Objective 2: To quantify how long-term manure additions to soil alter soil health, yearly samples will be collected and analyzed from a 12 year-long fertilizer study comparing commercial fertilizer with manure to meet the nitrogen needs for a corn silage crop that was terminated approximately 15 years ago. Both treatments had a cover crop and a no-cover crop treatment. Samples were collected following corn harvest in October 2023 and 2024. Data have been analyzed.
Accomplishments
1. Diatomaceous earth and flocculation remove antimicrobials from beef wastewater. Antimicrobials used in animal agriculture can potentially be released into the environment where they can cause antimicrobial resistance. Flocculation is a common wastewater treatment method used to clump small particles together to allow for filtration. ARS scientists at Clay Center, Nebraska, demonstrated that diatomaceous earth, a naturally occurring soft sedimentary rock, when used as a filter, removed 99% of tylosin, and 80% of chlortetracycline from wastewater generated from beef production, but ceftiofur in the wastewater remained in the solution. The combination of flocculation followed by application of diatomaceous earth in a two-step wastewater treatment process resulted in 100% removal of tylosin by diatomaceous earth and 100% removal of chlortetracycline by flocculation. The combination of the two methods improved the removal of chlortetracycline to 93.8%. The use of this mitigation tool will reduce the release of antimicrobials into the environment from livestock waste.
Review Publications
Stromer, B.S., Woodbury, B.L., Williams, C.F., Spiehs, M.J. 2024. Combined treatment methods for removal of antibiotics from beef wastewater. ACS Omega. 9(49):48721-48726. https://doi.org/10.1021/acsomega.4c08114.
Avramenko, A.G., Spiehs, M.J. 2024. Photophysical properties of porphyrins and their applications to polariton chemistry. Issues of Chemistry and Chemical Technology. 3:5-15. http://doi.org/10.32434/0321-4095-2024-154-3-5-15.