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ARS Home » Southeast Area » Fayetteville, Arkansas » Poultry Production and Product Safety Research » Research » Research Project #431658

Research Project: Quantifying Air and Water Quality Benefits of Improved Poultry Manure Management Practices

Location: Poultry Production and Product Safety Research

2019 Annual Report

The goal of this project is to reduce the negative environmental impacts of poultry litter on air, soil and water resources, while improving the agronomic value of this resource. We will measure runoff losses from pastures and aerial emissions from poultry facilities and develop/test Best Management Practices (BMPs) to reduce these losses. We will also measure the potential sources of acidification of the Mulberry River. The objectives of this research are: Objective 1. Quantify and track losses of nutrients, metals, soil and pathogens from pastures fertilized with poultry manure and develop and test management practices that reduce water quality impacts. Sub-objective 1A. Determine the long-term effects of overgrazing, rotational grazing, haying, and buffer strips on nutrient and sediment runoff from pastures. Sub-objective 1B. Determine the long-term effects of alum-treated and normal poultry litter applications on legacy P in soils, and on soil chemistry, P runoff and P leaching. Sub-objective 1C: Compare nutrient and pathogen runoff from small watersheds fertilized with poultry litter that is applied using litter incorporation or by broadcasting. Sub-objective 1D. Utilize P runoff from 24 small watersheds to validate the Arkansas P index. Objective 2. Measure gaseous and particulate emissions from poultry houses and develop and test management practices to reduce air pollution and nutrient losses. Sub-objective 2A. Measure NH3, dust and greenhouse gas concentrations and emissions from poultry houses. Sub-objective 2B. Determine the efficacy of an NH3 scrubber on reducing the emissions of dust and NH3 from poultry houses. Sub-objective 2C. Measure forage growth, N uptake and P runoff from small plots fertilized with N-rich scrubber solutions and commercial N fertilizer. Sub-objective 2D. Develop/test a cost-effective litter amendment that reduces NH3 emissions and P runoff. Objective 3. Quantify amounts of acid generated from different sources in the Mulberry River Watershed. Sub-objective 3A. Measure atmospheric NH3 and wet deposition of acid in the Mulberry River watershed. Sub-objective 3B. Compare various measures of soil acidification under hardwood and pine forests at multiple paired locations within the Mulberry River Watershed. Sub-objective 3C. Evaluate the relationship between water chemistry and the percentage of forest in pines within several sub-watersheds of the Mulberry River.

The objective of this research is to reduce the negative environmental impacts of poultry litter on air, soil and/or water resources, while improving the agronomic value of this resource. To meet this goal we propose to conduct research which investigates the nature of problems associated with poultry litter, determines the extent of these problems, and provides solutions to them. Both long-term and short-term studies will be conducted. One of the long-term (20 year) studies initiated in 2003 utilizes 15 small watersheds to determine the impacts of pasture management strategies (over grazing, rotational grazing, buffer strips, riparian buffer strips and haying) on pasture hydrology, erosion and nutrient and pathogen runoff. Another watershed study will evaluate the effect of two litter application methods on nutrient runoff. Two other long-term studies (paired watershed and small plot study) initiated in 1995 will evaluate the legacy effects of fertilizing with normal poultry litter or litter treated with alum on phosphorus (P) runoff and leaching. The watershed studies described above will also be utilized to validate the Arkansas P Index. Experiments will be conducted to evaluate the effectiveness of ammonia (NH3) scrubbers on reducing NH3 and dust emissions from poultry houses. Research will be conducted in the Mulberry River Watershed to determine if river acidification is occurring because of atmospheric NH3 deposition or other causes, such as acid rain or forestry practices. The ultimate goal of this research is to develop cost-effective best management practices (BMPs) for poultry manure management which improve air and water quality.

Progress Report
Progress was made on all objectives and subobjectives, all of which fall under National Program 212. Under Subobjective 1A, we made progress in conducting long-term research to reduce nutrient (phosphorus) runoff. The results of this 15-year study showed that phosphorus runoff was not different from pastures that had been overgrazed by cattle versus rotationally grazed. However, phosphorus runoff was reduced by using unfertilized buffer strips, as well as fenced, unfertilized riparian buffers, and by converting pastures to hayfields. Runoff water from this study is also being evaluated to assess the changes in antimicrobial resistant bacteria over time and with various conservation management practices. Using metagenomic analyses, soil and water bacterial communities are being evaluated following long-term applications of combined cattle manure and poultry litter amendments and amendments solely of poultry litter. Results demonstrate that cattle manure and boiler chicken litter applications increase the prevalence of anthropogenic antibiotic resistant bacteria, however, conservation pasture management practices have the potential to disrupt resistant gene movement from soil to water systems. Overall, study results illustrate that antibiotic alternatives may result in better bird performance, increase soil microbial diversity, while improving food safety.

1. Developed precision agriculture decision support tool. Scientists from USDA/ARS in Fayetteville and Booneville, Arkansas, and University of Arkansas research partners developed a decision support tool that promotes the adoption of precision agriculture technologies such as auto-guided tractors and other self-propelled machinery that reduce over-application of on-farm nutrients and inputs by 10-20%. Researchers determined that auto-guided tractors reduce on-farm inputs by as much as 20% and save producers $10.8-13.5 million annually by improving gains in equipment efficiency and enhancing yields. Moreover, producers can also reduce the over-application of fertilizers and herbicides, which reduces the negative environmental footprint of crop production and avoids unintentional input costs to the producer. The team of federal and university researchers developed Tractor Guidance Analysis software for providing tailored estimates of the economic and environmental benefits of adopting automated tractor guidance technology. The software incorporates parameters tailored to reflect the size of different farming operations and generates estimates for: 1) actual reductions in seed, organic and inorganic fertilizer, and chemical inputs given differing terrain attributes; 2) efficiency gains and feasibility of technology adoption by determining break-even prices based on farming operation type, farm size, and capital investment requirements; and 3) subsequent soil health and water quality impacts from reducing agricultural inputs based on in-field data. This tool was released in 2018, and scientists have provided hands-on training to farmers and agricultural workers via field days and stakeholder meetings. To date, the Tractor Guidance Analysis software has been especially effective in advancing the use of auto-guided tractors and self-propelled machinery on pastures and small farms, operations that traditionally have not adopted precision agriculture technologies.

2. Determined effectiveness of best management practices in reducing phosphorus runoff. Scientists from USDA/ARS in Fayetteville and Booneville, Arkansas, and University of Arkansas research partners conducted a long-term study to evaluate the effectiveness of grazing management and buffer strips on phosphorus runoff from pastures. Although phosphorus runoff from pastures fertilized with animal manure can cause serious water quality problems, long-term studies on the effectiveness of grazing management practices in combination with other best management practices, such as rotational grazing, have never been done. A 15-yr study was conducted on 15 watersheds with five treatments: hayed, continuously grazed, rotationally grazed, rotationally grazed with an unfertilized buffer strip, and rotationally grazed with an unfertilized fenced riparian buffer. The results showed that rotational grazing alone did not reduce phosphorus loads in runoff compared to continuous grazing. However, phosphorus runoff was reduced by 36% with unfertilized buffer strips, 60% with fenced, unfertilized riparian buffers and 49% by converting pastures to hayfields. These results show the use of buffer strips and converted pastures to hayfields can be very effective best management practices (BMPs) for reducing phosphorus runoff in Southeastern U.S. pastures. The data can also be used to determine weighting factors for BMPs in phosphorus indices used for nutrient management planning.

Review Publications
Braden, I.S., West, C.P., Ashworth, A.J. 2019. Spatial soil nutrient-plant-herbivore linkages: A case study from two poultry litter amended pastures in Northwest Arkansas. Agrosystems, Geosciences & Environment. 2:180036.
Toler, H.D., Auge, R.M., Benelli, V., Allen, F.L., Ashworth, A.J. 2019. Global meta-analysis of cotton yield and weed suppression from cover crops. Crop Science. 59:1-13.
Acharya, M., Burner, D.M., Ashworth, A.J., Felix, F., Adams, T. 2018. Growth rate of Giant Miscanthus (Miscanthus x giganteus) and Giant Reed (Arundo donax) in a low-input system in Arkansas, USA. American Journal of Plant Sciences. 9:2371-2384.
Popp, M.P., Ashworth, A.J., Moore Jr, P.A., Owens, P.R., Douglas, J.L., Pote, D.H., Jacobs, A., Lindsay, K. 2018. Fertilizer recommendations for switchgrass: Quantifying economic effects on quality and yield. Agronomy Journal. 110(5):1854-1861.
Pilon, C., Moore Jr, P.A., Pote, D.H., Martin, J.W., Owens, P.R., Ashworth, A.J., Miller, D.M., Delaune, P.B. 2018. Grazing management and buffer strip impact on nitrogen runoff from pastures fertilized with poultry litter. Journal of Environmental Quality. Available:
Burgess-Conforti, J.R., Moore Jr, P.A., Owens, P.R., Miller, D., Ashworth, A.J., Hays, P.D., Evans-White, M., Anderson, K.R. 2019. Are soils beneath coniferous tree stands more acidic than soils beneath deciduous tree stands? Environmental Science and Pollution Research. 26:14930–14931.
Ashworth, A.J., Lindsay, K.R., Popp, M.P., Owens, P.R. 2018. Economic and environmental impact assessment of tractor guidance technology. Agricultural and Environmental Letters. 3:1-5. Available:
Lepore, A., Ashworth, A.J., Pyoungchung, K., Labbe, N., Connatser, R.M., Allen, F.L. 2019. Feasibility and concurrent remediation of red mud as an in situ pyrolysis catalyst. BioResources. 14(2):4696-4707.
Lindsay, K.R., Popp, M.P., Ashworth, A.J., Owens, P.R. 2018. A decision - Support system for analyzing tractor guidance technology. Computers and Electronics in Agriculture. 153:115-125.
Adams, T., Philipp, D., Burner, D.M., Jennings, J., McPeake, B., Ashworth, A.J., Pote, D.H., Burke, J.M., Rhein, R. 2019. White (Trifolium repens L.) and arrowleaf (Trifolium vesiculosum Savi) clover emergence in varying loblolly pine (Pinus taeda L.) tree alley spacings. American Journal of Plant Sciences. 10:659-669.
Ashworth, A.J., Moore Jr, P.A., King, R., Douglas, J.L., Pote, D.H., Jacobs, A., Pratt, E. 2019. Switchgrass forage yield and compositional response to phosphorus and potassium. Agrosystems, Geosciences & Environment. 2:190010.