Location: Livestock Nutrient Management Research2017 Annual Report
Objective 1: Characterize and improve prediction of ammonia and greenhouse gas emissions from cattle production systems. Subobjective 1A. Characterize methane (CH4) emissions from southern Great Plains grazing systems. Subobjective 1B. Assess the impact of environmental conditions and management practices and their interactions on emissions of NH3 and GHG from open lot cattle production systems. Subobjective 1C. Improve NH3 and GHG emissions measurements for feedyards and dairies. Objective 2: Improve feed nutrient use in cattle to maintain animal productivity, reduce emissions of ammonia and greenhouse gases, and mitigate pathogens and antibiotic resistant bacteria. Subobjective 2A. Determine effects of cattle diet on enteric CH4 production. Subobjective 2B: Evaluate and improve models to predict enteric CH4 emissions from grazing and feedyard cattle. Subobjective 2C. Identify and quantify sources of enteric nitrous oxide (N20) emissions from cattle in respiration calorimetry chambers. Objective 3: Manage soil and manure reactive nitrogen, phosphorus and carbon to improve soil properties, reduce nutrient loss and mitigate pathogens and antibiotic resistant bacteria. Subobjective 3A. Evaluate the effectiveness, practicality and economics of chemical inhibitors and manure amendments to reduce N20 and NH3 emissions from beef cattle feedyards, dairies, and manure-amended soils. Subobjective 3B. Quantify field-scale emissions of N20 from manure-amended soils. Subobjective 3C. Establish protocols for examining AR in agroecosystems. Subobjective 3D. Characterize forms of P in manure-amended soils. Subobjective 3E: Evaluate soil C/N change with land use on the southern High Plains.
Beef and dairy cattle production provide vital human nutrition and important economic activity. Cattle production, like all human endeavors, also contains environmental risks. This multidisciplinary research will help us to better understand and mitigate the environmental risks from cattle production systems on the Southern Great Plains. We will quantify and improve predictions of emissions of ammonia (NH3) and greenhouse gases (GHG) from cattle production systems. The research will focus on the predominant agricultural GHG emissions of methane (CH4) and nitrous oxide (N20). Sources of these emissions include grazing animals (enteric emissions), emissions from cattle, pen and lagoon surfaces at beef feedyards and dairies, and emissions from soils following land application of manure. We will determine the effects of cattle diet on enteric GHG emissions on scales that range from single animal to whole pastures, feedyards or dairies. We will test potential mitigation methods to reduce emissions from manure surfaces and cropped fields using controlled laboratory experiments followed by pilot-scale and field-scale experiments. We will quantify the changes in soil carbon (C), nitrogen (N), and phosphorus (P) from application of manure or land use change. A collaboration of ARS laboratories will test methods to characterize antibiotic resistant (AR) bacteria and genes from manure-impacted soil. Research results will provide science-based information and technologies for livestock producers, extension specialists, and regulators to protect air quality, manage feedyard and dairy manure, enhance production efficiency, and improve sustainability of livestock production.
FY17 was the first year of research of the new project plan "Improved Practices to Conserve Air Quality, Maintain Animal Productivity, and Enhance Use of Manure and Soil Nutrients of Cattle Production Systems for the Southern Great Plains". We approach project objectives with a research philosophy that uses a multidisciplinary approach, emphasizes multiple methods and independent approaches to answer questions, and employs these at multiple scales from lab bench to pastures and feedyards. We entered into Year 5 of the five-year NIFA Grazing Coordinated Agricultural Project, a multi-institutional effort to understand the effects of grazing cattle on greenhouse gas (GHG) and the resilience of grazing systems to climate change. ARS scientists at Bushland, Texas were key contributors to the field research and mitigation practices objectives of the project and served on the project leadership team. Bushland scientists were collaborators on two National Science Foundation proposals. Unit scientists also actively participated in the ARS-led Dairy Agroecosystem Working Group. All five FY17 milestones were fully met. We characterized emissions from cattle production systems using novel approaches to measure emissions of GHG (Objective 1). A methodology was designed to quantify enteric methane emissions from the cows grazing a tallgrass prairie pasture (1A1). It consisted of open path lasers to measure atmospheric methane concentration and two eddy covariance systems that independently measured methane and carbon dioxide fluxes. The system was deployed during a two-week intensive field campaign in collaboration with the ARS researchers at El Reno, Oklahoma. This campaign was conducted during the dormant season of the pasture and will be coupled with emission results from early growing season and late growing season campaigns to fully characterize emissions. Collaborating scientists from El Reno contributed independent measurements of enteric methane, forage quality and dry matter intake. We initiated monitoring of methane and carbon dioxide emissions from a High Plains pasture soil to answer the question of whether and to what magnitude such semiarid upland soils are sources or sinks of carbon (1A3). An eddy covariance system that directly measures fluxes of the two carbon-containing gases was deployed to provide multi-year flux data. A flux chamber system was designed and constructed for quantifying emissions of the greenhouse gas nitrous oxide from manure (1B2). The six chambers, each with 1 square meter footprint, were mounted on a rail system to allow indoor and outdoor research. Using a real-time analyzer, the system was optimized to quantify nitrous oxide concentrations in a short 60-second measurement period, compared with traditional methods that take 30 to 60 minutes. Numerous trials were conducted, which showed that nitrous oxide emissions increased with both increasing rainfall and temperature. Nitrous oxide emissions increased considerably between temperatures of 28 C and 32 C, and decreased at temperatures above 40 C. An additional instrument to measure ammonia and methane was acquired and incorporated into the cutting edge system. The controlling factors of nitrous oxide emission from beef manure were studied using laboratory incubation studies (1B1, 1B3). We determined that high environmental temperatures caused an immediate and large flush of nitrous oxide from manure after simulated rainfall. Very little nitrous oxide was emitted when temperatures were moderate or when manure was dry. Research also focused on determining the specific enzymatic route of nitrous oxide production and the types of microbes involved. Experiments to improve feed nutrient use of cattle to maintain animal productivity and reduce emissions of ammonia and greenhouse gases focused on testing the effects of different diets on emissions of individual animals (Objective 2). A series of trials was conducted to investigate the effect of cattle diet on emission of enteric methane (2A1). The gold standard for such studies is a method called respiration calorimetry. Chambers large enough to hold a steer are monitored for gas exchange, and feed intake is carefully measured. A newer method called the GreenFeed system is like a breathalyzer for cattle that can measure enteric methane loss from the mouth and nostrils. Eight crossbred Angus steers, trained to the GreenFeed feeding system and respiratory calorimetry chambers, were fed four diets. Cattle spent 5 days on the GreenFeed system, followed by 5 days in the calorimetry chamber, and finally 5 days on the GreenFeed system. A similar approach evaluated the effects of forage quality on enteric methane production (2A2). Rations of low, medium and high quality tallgrass prairie hay were fed to steers and emissions of methane monitored in respiration calorimetry chambers and with the GreenFeed system. Models that predict enteric methane from cattle were identified frjom the scientific literature and a database of measured methane emissions from cattle and their diets in a feedyard was built (2B1). Managing soil and manure nitrogen, phosphorus and carbon can improve soil properties, reduce nutrient loss and mitigate pathogens and antibiotic resistant bacteria (Objective 3). We explored the relationship between crop rotation and tillage practices, and soil carbon and soil health by extending research by the ARS scientists at Bushland, Texas to see if conservation management improved factors related to soil health, including soluble carbon concentrations and organic matter stability (3E1). We used advanced techniques to analyze historic soil samples to characterize soil carbon. Overall, there were few differences in soil organic matter properties after 36 years of wheat cropping with either sweet till or no till. Concentrations of soluble organic carbon decreased by 52 to 70%, regardless of management approach. The soluble carbon from wheat fields under stubble mulch management, a low-till system where crop residue is left on the soil surface, contained more lignin and simple carbon forms. Manure application can result in accumulation of soil phosphorus that is not readily available for plant uptake. Excess soil phosphorus can be transported in runoff and over-fertilize lakes, rivers and estuaries. We collaborated with ARS scientists in Auburn, Alabama to determine the effects of poultry litter application on phosphorus availability in agricultural soils with high aluminum and iron content, as found in the southeastern United States (3D1). We leveraged a state of the art microbiology laboratory and a skilled microbiologist by collaborating with ARS microbiologists in Lincoln, Nebraska using an innovative "virtual microbiologist" concept. The goal was to develop an assay to detect antibiotic resistance in agricultural production settings (3C1). A collection of 300 Escherichia coli isolates from various manure-impacted environments was screened for 14 different genes associated with tetracycline resistance using polymerase chain reaction (PCR). PCR methods were optimized to make the reactions more specific for the target gene. Four qPCR (quantitative PCR) assays that quantified genes associated with antibiotic resistance were performed as part of a reproducibility study with the ARS lab in Lincoln, Nebraska. qPCR is a technique that determines the number of copies of a specific gene in a sample. Different operators in different labs conducted identical reactions to evaluate reproducibility as part of qPCR validation. Genes of interest were associated with resistance to macrolide, sulfonamide, cephalosporins or monobactams.
1. Comprehensive review of the science of nitrous oxide in beef feedyards. Beef feedyards are a source of the greenhouse gas nitrous oxide, but measured emissions are inconsistent and vary widely because of differences in cattle management, weather, and challenges with measurement methods. Therefore, a comprehensive literature review conducted by ARS researchers in Bushland, Texas, and State College, Pennsylvania, and Texas A&M AgriLife Research in Amarillo, Texas identified inconsistencies in measured emissions, and evaluated factors related to nitrous oxide losses. Numerous knowledge gaps were identified and recommended for future research. This work was a featured article in the Journal of Environmental Quality.
2. Greenhouse gas emissions from manure more accurately and quickly measured. Nitrous oxide is a greenhouse gas emitted from cattle manure and soils. Nitrous oxide emissions have traditionally been measured using chambers that cover the emitting surface and rely on several gas samples collected over a 30 to 60 minute period. However, such methods provide poor time resolution, thus, ARS scientists from Bushland, Texas, and Texas A&M AgriLife Research, Amarillo, Texas, developed an improved method that relies on a real-time, continuous nitrous oxide analyzer to accurately quantify nitrous oxide emissions from manure and soil in only 60 seconds. The improved method resulted in faster and more accurate measurement of greenhouse gas emissions from manure that revealed new dynamics in nitrous oxide emissions.
3. Rainfall amount increases nitrous oxide emissions from open-lot beef cattle feedlots. Nitrous oxide is a greenhouse gas emitted from livestock manure, but little is known of factors effecting emissions. ARS scientists from Bushland, Texas, and Texas A&M AgriLife Research, Amarillo, Texas, studied how rainfall affects nitrous oxide emissions from beef cattle feedlot manure. Nitrous oxide emissions were monitored after applying simulated rainfall to dry manure at five different rainfall amounts between 0 and 2 inches. Nitrous oxide emissions were elevated for 45 days after rainfall. These results indicate that improved drainage from feedlot pens will help to reduce nitrous oxide emissions from livestock manure.
4. Better analytic tools improve manure management. Analytical techniques to study manure are usually based on methods developed for soils, but these may be inadequate or inappropriate. Therefore, ARS researchers in Bushland, Texas and the New Orleans, Louisiana, and the University of Minnesota collaborated on an invited review paper that highlighted advanced and novel analytical techniques for manure. Spectroscopic methods, modified extraction techniques, and other techniques have vastly improved the characterization of organic matter, nitrogen and phosphorus in manure. These techniques will help develop improved manure management practices that minimize environmental risk while improving manure fertilizer value.
5. Simple and accurate methods estimate nitrous oxide emissions from beef feedyards. Cattle production contributes to emission of the greenhouse gas nitrous oxide, but studies have shown that feedyard nitrous oxide emission rates are highly variable. ARS researchers with in Bushland, Texas and Texas A&M AgriLife in Amarillo, Texas looked at how regional weather and manure characteristics affect nitrous oxide emission rates. Using field study data, mathematical models were developed to predict nitrous oxide losses based on easily measured manure properties. These included concentrations of nitrate and soluble carbon, water content, organic matter stability, and temperature. Emission estimates made with the new models agreed well with emission rates measured at feedyards. These models can help determine how changing climate and management affect the environmental footprint of beef production.
Walters, L., Cole, N.A., Jennings, J., Hutcheson, J., Meyer, B.E., Schmitz, A.N., Reed, D.D. 2016. The effect of zilpaterol hydrochloride supplementation on energy metabolism and nitrogen and carbon retention of steers fed at maintenance and fasting intake levels. Journal of Animal Science. 94:4401-4414. doi:10.2527/jas2016-0612.
Weiss, C.P., Gentry, W.W., Meredith, C.M., Meyer, B.E., Cole, N.A., Tedeschi, L.O., Mccollum, F.T., Jennings, J.S. 2017. Effects on roughage inclusion and particle size on digestion and ruminal fermentation characteristics of beef steers. Journal of Animal Science. 95:1701-1714. doi:10.2527/jas2016.1330.
Waldrip, H., Todd, R.W., Parker, D.B., Cole, N.A., Rotz, C.A., Casey, K. 2016. Nitrous oxide emissions from open-lot cattle feedyards: A review. Journal of Environmental Quality. doi:10-2134/JEQ2016.04.0140.
He, Z., Pagliari, P.H., Waldrip, H.M. 2016. Applied and environmental chemistry of animal manure: A review. Pedosphere. 26:779-816.
Parker, D.B., Waldrip, H., Casey, K.D., Todd, R.W., Willis, W.M., Webb, K. 2017. Temporal nitrous oxide emissions from beef cattle feedlot manure following a simulated rainfall event. Journal of Environmental Quality. 46:733-740 doi:10.2134/jeq2017.02.0042.
Maurer, D., Koziel, J., Bruning, K., Kroeger, K., Parker, D.B. 2016. Pilot-scale testing of renewable biocatalyst for swine manure treatment and mitigation of odorous VOCs, ammonia and hydrogen sulfide emissions. Atmospheric Environment. 150:313-321.