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.
Subobjective 2D. ARS researchers made progress developing and testing cost-effective litter amendments. Pen trials were conducted to test the efficacy of alum mud litter amendment which is a mixture of alum mud (a byproduct of alum manufacture), bauxite and sulfuric acid. Two pen trials were conducted using in which alum mud litter amendment was compared to alum and untreated control litter. The study showed this new amendment, which was developed by scientists at Fayetteville, reduces ammonia emissions as well as alum, even though production cost for this material should be half that of alum. Also, discovered why alum has not been reducing soluble phosphorus in litter as well as in the past and found that additions of calcium-based nanoparticles applied in conjunction with alum or sodium bisulfate (another product used for ammonia control in poultry houses) greatly reduced soluble phosphorus levels.
1. Tested alum mud litter amendment (AMLA) for reducing ammonia volatilization. Ammonia emissions from poultry litter cause poultry production and environmental problems. Many of these problems can be reduced using alum or other ammonia control products. Alum mud is a byproduct remaining after alum manufacture using sulfuric acid extraction of bauxite. Lab studies have shown that AMLA (a litter amendment composed of alum mud, bauxite and sulfuric acid which was patented by an ARS researcher in Fayetteville, Arkansas, reduced NH3 emissions and soluble P in poultry litter. In order to determine the efficacy of AMLA in reducing NH3 emissions under more real-world conditions, three pen trials were conducted. Litter amendments were made prior to chick placement. Compared with untreated litter, AMLA reduced overall NH3 emissions by 27% to 52% which was not significantly different from reductions in emissions by alum (35%). Alum mud litter amendment reduced cumulative NH3 losses from litter as much as, and in some cases more than, alum applied at the same rate. This study indicates that AMLA, which can be manufactured for a much lower price than alum and is an effective alternative litter amendment for reducing NH3 emissions from poultry litter. It is also a very sustainable practice because it utilizes a byproduct that is currently being landfilled at $32 per ton.
2. Developed a new manure amendment to reduce soluble phosphorus. Phosphorus runoff and NH3 emissions are two of the biggest environmental problems associated with poultry production. Additions of alum to poultry litter, a best management practice developed and patented by our unit, reduces NH3 volatilization from litter, as well as P runoff and leaching. Due to the economic benefits from improved poultry performance alum is currently used to grow approximately 40% of the broiler chickens in the USA. However, recently alum additions to litter have not always resulted in the same reduction in soluble P as in the past. In fact, alum additions were found to increase soluble P in litter that had been treated with sodium bisulfate, a popular ammonia-control product sold under the trade name Poultry Litter Treatment (PLT). This is likely due to the formation of sodium alunite, a mineral that inactivates the aluminum with respect to P adsorption and precipitation reactions. Phosphorus solubility also increases in litter treated with PLT. While conducting research on this problem, ARS researchers in Fayetteville, Arkansas, discovered that additions of small amounts of calcium-based nanoparticles to litter treated with alum and/or PLT caused a synergistic reaction resulting in very low soluble P. A patent application was submitted on this technology. This research indicates that poultry litter treatments used for ammonia control to grow about 80% of the broilers in the USA (alum and PLT) could be greatly improved by this technology, thus reducing non-point source P pollution and improving water quality.
3. Developed a management recommendation for an ARS implement that minimizes nutrient losses to the air, soil, and water. Poultry production in the southeastern U.S. is a leading enterprise, as about half of the national broiler (meat chicken) production occurs in four southeastern states. Furthermore, use of by-products from poultry production, or the mixture of manure and bedding material, has the potential to close nutrient loops, as animal by-products are re-applied the following season to marginal soils. Although, conventional application methods entail evenly spreading poultry litter on the soil surface, which can result in up to 60% of the nutrients being lost to the air, soil, and water. In efforts to improve management options that aid in nutrient sustainability and improve crop yield, ARS researchers in Fayetteville, Arkansas, developed a prototype tractor-drawn implement for subsurface applications of dry poultry litter in conservation tillage systems. This sub-surface method for applying litter or the ‘subsurfer’ lowers nutrient runoff and ammonia emissions by at least 90%. Corn is arguably the world’s most important food crop owing to its diverse uses for animal fodder, cellulosic and grain-based ethanol, and primary and secondary products being consumed by humans. A study was conducted at three sites in Arkansas and Alabama by ARS researchers in Fayetteville, Arkansas, and ARS researchers in Auburn, Alabama, to evaluate optimum corn planting distances from sub-surface applied poultry litter for maximizing nutrient uptake and reduction of nutrient losses under rainfed and irrigated conditions. Overall, yield and crop quality results suggest sub-surface banding poultry litter 13-cm from corn rows may be a viable replacement for inorganic fertilizers in fodder and grain systems, particularly in organic production systems. Adoption of subsurface banding poultry litter relative to surface applications of poultry litter and inorganic fertilizers would enhance soil and water conservation while improving nutrient cycling, sustaining crop production, and on-farm profitability.
4. Developed a method for rapidly quantifying spatial overlaps and gaps for precision agriculture tools. ARS researchers in Fayetteville and Booneville, Arkansas, and University of Arkansas research partners developed an automated method for rapid determination of spatial coverage 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%. It is estimated that auto-guided tractors reduce on-farm inputs by as much as 20% and can 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. Currently, roughly half of large-scale row crop producers are using tractor guidance, however, 82% of the total farms in the US are small farms but are largely not adopting these cost and environmental saving technologies. Therefore, this team: 1) developed a method to calculate overlaps and gaps, and 2) quantified overall gains by tractor guidance systems. Field research was conducted using fertilizer (inorganic and poultry litter) and sprayer applications with and without tractor guidance. USDA-ARS researchers developed a novel automated method for quantifying overlaps and gaps and proposes a new method for calculating spatial coverage efficiency. Results suggests that tractor guidance systems reduce overlaps (up to 6% of the total field area) and gaps (up to 16%) during field operations and improves the average overall efficiency by 8%. Hence, tractor guidance systems likely result in reduced input-use and shorter in-field operation time leading to improved economic and environmental savings. Our approach to estimate tractor guidance efficiency on small farms using actual field research is novel and may aid in adoption of tractor guidance, thus potentially improving efficiency gains on 82% of U.S. farms.
Acharya, M., Ashworth, A.J., Burner, D., Burke, J.M., Pote, D.H., Muir, J.P. 2019. Browse potential of bristly locust, smooth sumac, and sericea lespedeza for small ruminants. Agroforestry Systems. https://doi.org/10.1007/s10457-019-00479-0.
Ashworth, A.J., Knapp, V., Allen, F.L., Saxton, A.M. 2020. Comparing yield trial locations based on their elicited expressions of genetic variance among soybean cultivars. Crop Science. 60:1313–1324. https://doi.org/10.1002/csc2.20066.
Rocateli, A.C., Ashworth, A.J., West, C.P., Brye, K.R., Popp, M.P., Kiniry, J.R. 2020. Simulating switchgrass biomass productivity using ALMANAC. I. Calibration of soil water. Agronomy Journal. 112:183-193. https://doi.org/10.1002/agj2.20054.
Yang, Y., Ashworth, A.J., Debruyn, J.M., Willett, C., Durso, L.M., Cook, K.L., Moore Jr, P.A., Owens, P.R. 2019. Soil bacterial biodiversity is driven by long-term pasture management, poultry litter, and cattle manure inputs. PeerJ. 7:e7839. https://doi.org/10.7717/peerj.7839.
Kelsey, A.R., Moore Jr, P.A., Pilon, C., Owens, P.R., Ashworth, A.J., Miller, D., Delaune, P. 2020. Long-Term effects of grazing management and buffer strips on phosphorus runoff from pastures fertilized with poultry litter. Journal of Environmental Quality. 49:85-96. https://doi.org/10.1002/jeq2.20010.
Ashworth, A.J., Owens, P.R., Allen, F. 2020. Long-term cropping systems management influences soil strength and nutrient cycling. Geoderma. 361. Article 114062. https://doi.org/10.1016/j.geoderma.2019.114062.
Amorim, H.C., Ashworth, A.J., Wienhold, B.J., Savin, M.C., Allen, F.L., Saxton, A.M., Owens, P.R., Curi, N. 2020. Soil quality indices based on long-term conservation cropping systems management. Agrosystems, Geosciences & Environment. 3(1). Article e20036. https://doi.org/10.1002/agg2.20036.
Ashworth, A.J., Pote, D.H., Way, T.R., Watts, D.B. 2020. Effect of seeding distance from subsurface banded poultry litter on corn yield and leaf greenness. Agronomy Journal. 112:1679-1689. https://doi.org/10.1002/agj2.20186.
Kharel, T.P., Ashworth, A.J., Shew, A., Popp, M.P., Owens, P.R. 2020. Tractor guidance improves production efficiency by reducing overlaps and gaps. Agricultural & Environmental Letters. 1(5). Article e20012. https://doi.org/10.1002/ael2.20012.
Anderson, K., Moore Jr, P.A., Martin, J.W., Ashworth, A.J. 2020. Effect of a new manure amendment on ammonia emissions from poultry litter. Atmosphere. 11(3). Article 257. https://doi.org/10.3390/atmos11030257.
Ashworth, A.J., Moore Jr, P.A., King, R., Douglas, J.L., Pote, D.A., Jacobs, A. 2020. Switchgrass nitrogen fertility response and nutrient cycling in a hay system. Agronomy Journal. 112:1963-1971. https://doi.org/10.1002/agj2.20156.
Amorim, H., Ashworth, A.J., Moore Jr, P.A., Wienhold, B.J., Savin, M.C., Owens, P.R., Jagadamma, S., Carvalho, T.S., Sutie, X. 2020. Soil quality indices following long-term conservation pasture management practices. Agriculture, Ecosystems and Environment. 301. Article 107060. https://doi.org/10.1016/j.agee.2020.107060.