1a. Objectives (from AD-416):
1) Determine the factors that affect P transformations and transport in soil, water and manure. 1A. Utilize P runoff from 25 small watersheds to validate the Arkansas P index. 2) Determine the long-term impacts of grazing management and treating manure with alum on nutrient and water transport processes and air emissions. 2A. Determine the long-term effects of overgrazing, rotational grazing, haying, and buffer strips on nutrient and sediment runoff from pastures. 2B. Determine the long-term effects of treating poultry litter with alum on NH3 emissions, soil chemistry, P runoff and leaching, and forage yields. 3) Develop and evaluate best management practices to reduce non-point P pollution from poultry litter application on pasture land. 3A. Compare nutrient runoff and hydrology from small watershed fertilized with poultry litter using three different methods. 4) Determine ammonia emission rates from poultry litter and develop best management practices to control ammonia volatilization. 4A. Determine the effect of in-house composting of poultry litter on emissions of ammonia and greenhouse gases. 4B. Determine the efficacy of an NH3 scrubber on reducing the emissions of dust and NH3 from poultry houses. 4C. Determine the effect of alum additions to broiler litter on emissions of NH3, volatile organic compounds (VOCs), and dust. 5) Determine the sources and loss pathways of bacterial pathogens associated with animal manures and develop cost-effective best management practices (BMPs) to mitigate pathogen runoff. 5A. Measure pathogen and indicator organisms in runoff from 25 small watersheds fertilized with manure or biosolids. 5B. Determine the impact of BMPs on pathogen runoff from poultry litter. 6) Evaluate the risks and benefits of agricultural applications of municipal wastes (biosolids and water treatment residuals) and develop formulations and application methods that enhance the value of these resources while reducing negative environmental impacts.
1b. Approach (from AD-416):
Both long-term and short-term studies will be conducted. Two 20-year studies will be conducted to determine the long-term impacts of poultry litter, alum-treated litter, and ammonium nitrate on soil chemistry, nutrient runoff, and forage production. A long-term study (13 years) will also be conducted on the impacts of various pasture management strategies (overgrazing, rotational grazing, haying, etc.) on pasture hydrology, nutrient runoff, soil erosion, and forage production. Another long-term study (7 years) will be conducted to determine the effects of pasture renovation and litter incorporation on P runoff, ammonia emissions and forage yields. Pathogen runoff will also be evaluated from both small plots and at the field scale. Ammonia emissions will also be measured from commercial broiler houses using various management 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 our main focus has continued to be on building and testing our redesigned ammonia scrubber for poultry houses. Trials were conducted on how the scrubber performed under varying ventilation rates and when the concentration of ammonia varied. Although the efficiency of the scrubber was reduced slightly as air flow or ammonia concentration increased, the mass of nitrogen captured was significantly increased. We also found that many acids were unsuitable for use in the ammonia scrubber for a variety of reasons. Strong acids are too dangerous for farmers to use. Some dry acids, such as alum, would not readily dissolve. All of the acid salts of aluminum and iron would form aluminum and iron hydroxides, which coated the insides of the scrubber and would likely greatly reduce air flow and increase static pressure over time. Although sodium bisulfate did not cause any of these problems, the fertilizer produced with this acid was sodium based, which could result in sodic soil conditions if used over long periods of time. Finally we found that potassium bisulfate worked as well as sodium bisulfate with regard to its physical properties, but resulted in a much more sustainable fertilizer (ammonium potassium sulfate).
Wood, W.C., Moore Jr., P.A., Joern, B.A., Jackson, R.D., Cabrera, M.L. 2012. Nutrient management on pasture and haylands. In: Nelson, C.J., editor. Conservation Outcomes from Pastureland and Hayland Practices: Assessment, Recommendation, and Knowledge Gaps. Lawrence, KS:Allen Press. p. 258-314.