1a. Objectives (from AD-416):
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. Subobjective 1A. Determine the long-term effects of overgrazing, rotational grazing, haying, and buffer strips on nutrient and sediment runoff from pastures. Subobjective 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. Subobjective 1C: Compare nutrient and pathogen runoff from small watersheds fertilized with poultry litter that is applied using litter incorporation or by broadcasting. Subobjective 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. Subobjective 2A. Measure NH3, dust and greenhouse gas concentrations and emissions from poultry houses. Subobjective 2B. Determine the efficacy of an NH3 scrubber on reducing the emissions of dust and NH3 from poultry houses. Subobjective 2C. Measure forage growth, N uptake and P runoff from small plots fertilized with N-rich scrubber solutions and commercial N fertilizer. Subobjective 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. Subobjective 3A. Measure atmospheric NH3 and wet deposition of acid in the Mulberry River watershed. Subobjective 3B. Compare various measures of soil acidification under hardwood and pine forests at multiple paired locations within the Mulberry Watershed. Subobjective 3C. Evaluate the relationship between water chemistry and the percentage of forest in pines within several sub-watersheds of the Mulberry River.
1b. Approach (from AD-416):
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.
3. Progress Report:
During the past year we conducted a study using soil cores taken from a long-term alum study initiated in 1995 in order to determine the legacy effects of fertilizers on phosphorus leaching. This study used 52 small plots to evaluate the effect of 13 treatments (an unfertilized control, four rates of alum-treated poultry litter, four rates of normal litter and four rates of ammonium nitrate) on soil chemistry, phosphorus leaching and runoff, and plant growth. New building construction by the Division of Agriculture, University of Arkansas on the farm in 2017 resulted in the loss of these long-term leased research plots. Prior to construction, we took two soil cores from each plot to measure the legacy effects of fertilization on P leaching (total of 104 cores). One of the cores from each plot was unfertilized and the other core received the same type and amount of fertilizer as they had the previous 20 years. Results of this study indicate that litter application during the past year had no effect on phosphorus leaching, as it was dependent on previous long-term manure applications. This year we completed a 12-year systems research project assessing soil health and crop yield impacts from crop rotations (ranging from monocultures to more temporally diverse sequences of soybean, corn, and cotton), cover crops, and poultry litter. Scientists, in collaboration with the University of Tennessee and the Booneville, Arkansas, ARS unit, determined that poultry litter amendments improve soil health and yield compared to inorganic fertilizers and cover crops in cropping systems. Researchers also found that greater cropping rotation complexity in 4-yr cycles resulted in an 8% increases in crop yields compared to continuous systems. Long-term poultry litter applications resulted in greater soil fertility and soil organic carbon storage. After 12-years of poultry litter applications, crop yields increased 11% across locations compared to cover crops. Soil amendments greatly impacted soil microbial and earthworm abundance, with poultry litter amended soils differing from wheat and hairy vetch cover crops. Therefore, soil microbial and earthworm diversity was greatest under poultry litter and less pesticide-intensive crop rotations of corn and soybean compared to cotton. These results suggest that soil ecosystem services and soil health are improved under nutrient-rich poultry litter and high residue producing crop rotations.
1. Discovered that nitrogen captured using an ammonia scrubber was as good as or better than commercial nitrogen fertilizer. One of the biggest environmental problems associated with the poultry industry is ammonia emissions from poultry houses, which cause air and water pollution. Scientists at Fayetteville, Arkansas, have developed the ARS Air Scrubber, which captures ammonia and dust emitted from poultry houses. This year we found that when tall fescue plots were fertilized with scrubber solutions containing nitrogen captured from poultry house emissions using alum, potassium bisulfate, sodium bisulfate, or sulfuric acid, the yields were equal to or greater than ammonium nitrate fertilizer applications at the same rate of nitrogen (100 pounds per acre). The potential impact of this research is enormous, since in Arkansas alone over 100 million pounds of ammonia are emitted each year from poultry houses which could be captured and used as fertilizer.
2. Discovered that in-house windrowing between flocks of birds in broiler houses significantly increases ammonia and nitrous oxide emissions. Currently, broiler chicken producers in the U.S. often windrow poultry litter in commercial houses between flocks of birds. This practice is typically called in-house composting (although it does not produce compost) and is believed to reduce the number of pathogens in the litter since temperatures of 50 to 65°C are produced. Scientists in Fayetteville, Arkansas, working with ARS scientists from Florence, South Carolina, and Beltsville, Maryland, measure the effects of windrowing litter in commercial broiler houses located in norhwest Arkansas. Effects of windrowing on pathogens in litter are inconclusive; however, windrowing increased ammonia emissions from 13.7 to 21.4 kg/house-day. Likewise, windrowing increased nitrous oxide emissions from 0.31 to 1.65 kg/house-day. Although more research is needed to determine the effect of this practice on pathogens and disease control, these data indicate that this practice likely results in increased air pollution from broiler houses.
Ashworth, A.J., Allen, F., Saxton, A.N., Tyler, D. 2017. Impact of crop rotation and soil amendments on long-term no-tilled soybean yields. Agronomy Journal. 109(3):1-9.
Pilon, C., Moore Jr, P.A., Pote, D.H., Pennington, J.H., Martin, J.W., Brauer, D.K., Raper, R.L., Dabney, S.M., Lee, J. 2017. Long-term effects of grazing management and buffer strips on soil erosion from pastures. Journal of Environmental Quality. 46(2):364-372. doi:10.2134/jeq2016.09.0378.
Ashworth, A.J., Rocateli, A.C., West, C.P., Brye, K., Popp, M.P. 2017. Switchgrass growth and effects on biomass accumulation, moisture content, and nutrient removal. Agronomy Journal. 109:1-9.
Ashworth, A.J., Allen, F.L., Tyler, D.D., Pote, D.H., Shipitalo, M.J. 2017. Earthworm populations are affected from long-term crop sequences and bio-covers under no-tillage. Pedobiologia. 60:27-33.
Pilon, C., Moore Jr, P.A., Pote, D.H., Martin, J.W., Delaune, P.B. 2017. Effects of grazing management and buffer strips on metal runoff from pastures fertilized with poultry litter. Journal of Environmental Quality. 46(2):402-410.
Ashworth, A.J., Weiss, S.A., Keyser, P.D., Allen, F.L., Tyler, D.D., Taylor, A., Beamer, K.P., West, C.P., Pote, D.H. 2016. Switchgrass composition and yield response to alternative soil amendments under intensified heat and drought conditions. Agriculture, Ecosystems and Environment. 233:415-424.
Delaune, P.B., Moore Jr, P.A. 2016. Copper and zinc runoff from land application of composted poultry litter. Journal of Environmental Quality. 45(5):1565-1571.