Project : USDA ARS

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Research Project: Developing Best Management Practices for Poultry Litter to Improve Agronomic Value and Reduce Air, Soil and Water Pollution

Location: Poultry Production and Product Safety Research

2023 Annual Report

Objectives
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. 1A. Determine the long-term effects of continuous grazing, rotational grazing, haying, and buffer strips on nutrient, sediment, pathogen, and antibiotic resistant genes in runoff from pastures. 1B. Determine the long-term effects of alum-treated and normal poultry litter on legacy P in soils, and on soil chemistry, P runoff and P leaching. 1C. Determine the long-term effects of applying poultry litter either by incorporation or by broadcasting in nutrient runoff. 1D. Identify how plant species dynamics influences nutrient losses under long-term poultry litter applications in grazable filter strip systems. 2. Measure gaseous and particulate emissions from poultry houses to develop management practices to reduce air pollution and nutrient losses. 2A. Measure NH3, dust and greenhouse gas concentrations and emissions from poultry houses. 2B. Evaluate the effects of a photocatalytic ammonia removal device on ammonia levels in poultry houses. 2C. Conduct pen trials with broiler chickens to determine the efficacy of existing and new litter amendments on NH3 volatilization. 2D. Measure forage growth, N uptake and P runoff from small plots fertilized with poultry litter from pen trials using poultry litter treated with various litter amendments. 3. Quantify the environmental impacts, crop responses, and profitability of using precision technology for nutrient management to increase the sustainability of systems agriculture. 3A. Quantify nutrient dynamics following subsurface banding of litter for development of improved management recommendations and enhanced yield in both hay and row crop systems. 3B. Identify factors influencing precision agriculture technology efficiencies for improved economic viability and reduced negative environmental impacts through decision support tools. 3C. Develop and evaluate potential changes to the Arkansas Phosphorus Index. 3D. Quantify macropore flow and phosphorus leaching based on landscape attributes. 4. Develop new, useful technologies to remove and recover nutrients from poultry litter to improve on-farm use and reduce loss to the environment. 4A. Develop strategies for improved poultry litter recycling. 4B. Develop a cost-effective ammonia scrubber for animal rearing facilities.

Approach
Agricultural landscape management and production practices are linked to environmental quality and ecosystem services. However, research is lacking on technologies that assist in sustainable intensification and lead to greater economic returns for end-users at the systems-level. 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 challenge, we will investigate issues preventing the sustainable use of poultry litter and develop solutions through data and technology-use. 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. In addition, short-term studies will evaluate multifunctional grazing strips, precision placement of poultry litter, and precision agriculture’s ability to reduce adverse water quality impacts during fertilization. An additional experiment will evaluate subsurface phosphorus (P) leaching from macropores in areas with highly permeable bedrocks, such as ‘karst’ topographies. The watershed studies and column experiment 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. The ultimate goals of these research projects are to develop cost-effective best management practices (BMPs) for poultry manure management that improve air and water quality, as well as overall system-level sustainability.

Progress Report
Progress was made on all objectives and subobjectives, all of which fall under National Program 212. Under Objective 1, studies quantifying and tracking losses of nutrients, metals, soil and pathogens from pastures fertilized with poultry manure are underway in a series of watershed and rainfall simulation studies with preliminary data collected. Progress was made on Objective 2’s efforts to measure gaseous and particulate emissions in poultry houses to ultimately develop best management (BMP) strategies to reduce air pollution. Additionally, research was undertaken to address Objective 3 (quantifying the impact of precision agriculture technology for optimizing nutrient management and increase the sustainability of systems agriculture). Finally, research was initiated to address Objective 4, focused on developing new and affordable technologies to remove and recover nutrients from poultry litter to improve on-farm use and reduce losses to the environment.

Accomplishments
1. Tested soil nutrient-forage crop dynamics from poultry litter amended alum in grassland systems. Although adding alum to poultry litter is a well-known best management practices (BMP) for reducing ammonia emissions and P runoff, scant information is available on the effects of treating poultry litter with alum on forage yield, and soil nutrient and metal availability. ARS researchers in Fayetteville, Arkansas, finalized a 20-year research trial evaluating if reducing soluble phosphorus in poultry litter via alum would result in forage nutrient deficiencies, metal toxicity, or reduce yields (relative to non-amended litter and ammonium nitrate at various rates). Study results found that ammonium nitrate had 34% yield reductions compared with poultry litter sources due to soil acidification and that nutrient deficiencies did not occur with alum-treated litter. Alum is a best management practice for improving air and water quality without causing pasture crop nutrient deficiencies. Currently over four billion broiler chickens are grown with alum each year in the U.S., with an economic impact of $50-60 million. Study results indicate that amending pasture soils with alum-treated litter does not adversely affect crop yields or nutrient utilization.

2. Developed first ever continuous soil property maps on Tribal Lands. Knowledge, data, and understanding is key for advancing agriculture and society, although not all sectors of U.S. societies have received information and technology transfer at the same rate. Tribal Reservations have very basic soil information relative to other producers in the U.S. ARS researchers in Fayetteville, Arkansas, created first ever high-resolution digital maps of soil properties of Quapaw Tribal Lands for sustainable soil resource management. New high-resolution soil property maps set the baseline for versioning and production of new spatial soil information for the Quapaw Tribal Land for crop suitability maps and sustainable intensification. These maps are now available via a Partnerships for Data (PDI) Innovations tool (“Tribal Soil Explorer”) and are being used for soil, crop, and land-use decisions at the farm and Tribal-level for increased agricultural productivity and economic growth. This research has trained >100 indigenous researchers on digital agricultural tools and is being expanded to Southwestern Tribal Nations to develop climate-smart tools.

3. Quantified source pollution potential of animal manures in karst geologies. Understanding the transmission of nutrients from land-applied animal manures to water bodies is important for implementing appropriate nutrient managements plans. This information is particularly needed in sensitive areas with highly permeable bedrock, such as in ‘karst’ topographies. These areas have direct soil surface to groundwater drainage although the extent of this is unknown. ARS researchers in Fayetteville, Arkansas, extracted large (45 cm diam. By 100 cm height) intact soil columns down to parent material and conducted experiments to quantify the nutrient leaching potential for soils underlaying karst and non-karst geologies. Researchers found that soils from karst landscapes had 6 times greater leachate volume and total leached nutrients than non-karst soils and that spatial locations of soils overlaying karst geologies should be identified for precision nutrient management planning. Results will be used to update the Arkansas Phosphorus Index and for on-farm precision nutrient management planning at the state-level.

4. Tested novel buffer strip species for their ability to improve edge of field water quality. Vegetative filter strip characteristics such as perenniality drive hydrology and subsequent ecosystem services. However, the extent and the potential for forage–biomass crops to improve water quality, provide fodder, and optimize nutrient cycling in multifunctional systems is unknown. ARS researchers in Fayetteville, Arkansas, tested newly released perennial small grains (Kernza and Silphium) alongside native warm-season grasses (switchgrass and gamagrass) against annual grains (wheat and rye) for their ability to limit non-point source pollution from broiler litter applications and provide fodder in dual-use systems. The performance of newly introduced perennial grain crops (Kernza and silphium) was similar or better than that of gamagrass in terms of sediment and nutrient losses in rainfall simulation studies. Results show there is a high potential for Kernza, silphium, and switchgrass to improve water quality when used in forage–vegetative filter strip systems.

5. Tested a novel strategy for valorizing poultry litter while evaluating portable devices capable of storing energy. Biochar applications to soils may enhance soil quality, hydrological properties, and agronomic productivity. Modification of biochar by activation via introduction of heteroatoms at different pyrolysis conditions may alter physical and chemical characteristics, which may enhance soil properties, although the extent of this is unknown. ARS researchers in Fayetteville, Arkansas, tested activated (activated with methanesulfonic acid) and unactivated biochar produced from poultry litter to identify optimum production conditions for end use as a soil amendment and energy source. Physical, chemical, and surface properties of biochars were determined using wet chemistry and spectroscopic analyses. Results showed that activation increased biochars’ oxygen content, while decreasing its point of zero charge and electrical conductivity. Conversion of raw poultry litter to activated and unactivated biochar increased concentration of P (3-fold), K (1.8-fold), Ca (3-fold), Mg (2.3-fold), and S (4.8-fold), with concentrations increasing with increasing temperatures. Activated biochar had lower recovery of C and N, but greater water-holding capacity than unactivated biochar. Therefore, poultry litter can be a value-added energy product and can improve soil quality via biochar.

U.S. DEPARTMENT OF AGRICULTURE

Poultry Production and Product Safety Research: Fayetteville, AR