Category: Waste to Worth

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A Decision-Support Tool for The Design and Evaluation of Manure Management and Nutrient Reuse in Dairy and Swine Farm Facilities

Purpose

The decision-support tool (DST) being developed facilitates the selection of manure treatment technology based on farm needs and nutrient balance requirements. A life cycle assessment (LCA) approach is used to determine and allocate among sources the whole-farm greenhouse gas (GHG) emissions and environmental impact of different manure management systems (MMS) to facilitate decision-making. The purpose of the tool is to help users identify the suite of technologies that could be used, given the farm’s unique set of preferences and constraints. The tool asks for an initial set of farm details and these values are cross-checked with predefined conditions before starting the simulation. This tool helps in the rapid quantification and assessment of treatment technology feasibility, GHG emissions, environmental, and economic impacts during the manure management decision-making process (Fig. 1). The decision algorithm operates based on user input for weightage priorities of criteria and sub-criteria related to environmental, economic, and technical components.

Figure 1. Graphical abstract

What Did We Do?

The DST is a Microsoft Excel-based tool with precalculated mass balance for a selected number of MMS alternatives representing current and emerging treatment technologies and practices. The MMS considered for the tool includes various handling systems, aerobic and anaerobic treatment systems, solid-liquid separation techniques, chemical processing units, etc. Modules were developed based on mass and energy balances, equipment capital & operating costs, unit process, and technology performance, respectively. The tool utilizes data specific to the country/region/farm where feasible and default values to calculate the overall economic and environmental performance of different MMS, providing results unitized per animal/day or per year.

Then, an LCA approach is used to evaluate the potential environmental footprints of each MMS considered. A life cycle impact assessment (LCIA) is comprised of detailed quantification of inputs and outputs of material flows in a specific treatment and/or conversion process. At the output level, it also defines and quantifies the main product, co-products, and emissions. The major focus on the treatment methods is quantifying the raw materials (manure, wash-water, bedding, etc.) that are to be handled in each MMS, thereby characterizing the properties of effluents (nutrients, gas emissions, etc.). The results include carbon, energy, water, land, nitrogen, and phosphorus footprints along with the effluent nitrogen, phosphorous, and potassium concentrations.

What Have We Learned?

Systematic selection of appropriate technology can provide environmental and economic benefits. Manure management systems vary in their design, due to individual farm settings, geography, and end-use applications of manure. However, the benefits of technological advancements in MMS provide manure management efficiencies and co-production of valuable products such as recycled water, fiber, sand bedding, and nutrient-rich bio-solids, among others. The handling efficiencies and environmental benefits provided by manure treatment technologies come with additional costs, however, so the tradeoffs between environmental benefits and implementation costs also need evaluation.

Future Plans

The next steps are to finalize the dairy module. We are refining the tool’s user interface and demonstrating to stakeholders to gather information regarding key assumptions, outputs, and the functionality of the tool. Further, we also plan to complete the swine module.

Authors

Sudharsan Varma Vempalli, Research Associate, University of Arkansas

Corresponding author email address

svvempal@uark.edu

Additional authors

Sudharsan Varma Vempalli, Research Associate, University of Arkansas

Erin Scott, PhD Graduate Assistant, University of Arkansas

Jacob Allen Hickman, Project Staff, University of Arkansas

Timothy Canter, Extension Specialist, University of Missouri

Richard Stowell, Professor, University of Nebraska-Lincoln

Teng-Teeh Lim, Extension Professor, University of Missouri

Lauren Greenlee, Associate Professor, The Pennsylvania State University

Jennie Popp, Professor, University of Arkansas

Greg Thoma, Professor, University of Arkansas

Additional Information

Detailed economic impacts and tradeoffs expected with the implementation of certain MMS related to this tool is presented during the conference by Erin Scott et al., on the topic “Evaluating Costs and Benefits of Manure Management Systems for a Decision-Support Tool”.

Varma, V.S., Parajuli, R., Scott, E., Canter, T., Lim, T.T., Popp, J. and Thoma, G., 2021. Dairy and swine manure management–Challenges and perspectives for sustainable treatment technology. Science of The Total Environment, 778, p.146319. https://www.sciencedirect.com/science/article/pii/S0048969721013875

Acknowledgements  

We acknowledge funding support from the United States Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA) grant award (# 2018-68011-28691). We would also like to thank our full project team and outside experts for their guidance on this project.

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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Evaluating Costs and Benefits of Manure Management Systems for a Decision-Support Tool

Purpose

The purpose of the decision-support tool is to help livestock producers understand the costs of implementing new technology and the potential benefits associated with nutrient and water recovery, and how these compare across systems. Livestock agriculture is under increased scrutiny to better manage manure and mitigate negative impacts on the environment. At the same time, the nutrients and water present in manure management systems hold potential economic value as crop fertilizer and irrigation water. While technologies are available that allow for recovery and/or recycling of solids, nutrients and water, appropriate decision-support tools are needed to help farmers evaluate the practicality, costs, and benefits of implementing these systems on their unique farms.

What Did We Do?

In designing and refining the tool, we consider which economic components are important in driving the decision algorithm, as well as what is the most valuable economic output information for the user. We developed several “scenarios” defined by the unit processes used in the capture, treatment, storage, and usage of dairy manure. The costs and benefits related to each unit process were evaluated and aggregated for each scenario. Unit processes included flush/scrape activities, reception pit, sand recovery, solids separation, anaerobic digestion, composting, pond/lagoon storage, and tanker/drag hose land application.

Economic information was gathered from published literature, government documents, extension tools, and communication with academic, industry, and extension experts. We evaluated capital costs as an annual capital recovery value; operational costs including labor, energy, and repair and maintenance; cost savings resulting from sand/organic bedding and water reuse; fertilizer value of manure for use on-farm; revenue potential including the sale of treated manure nutrients and energy from anaerobic digestion; and the combined net costs or net benefits. Economic results are integrated into the multi-criteria decision algorithm. Results also elucidate economic tradeoffs across manure management systems (MMS), which can be used by farmers to assist in their decision-making.

What Have We Learned?

Economics is often about evaluating trade-offs between different choices or decisions. When evaluating results from the tool, we see that an increase in capital spending may lead to decreases in operational costs relative to capital costs, depending on farm size. This is due to a general reduction in labor and fuel costs associated with automated or additional manure treatment (e.g. increased spending on an MMS). For example, additional manure treatment can reduce land application expenses and increase cost savings from recovered sand or organic bedding. However, this larger capital outlay may or may not be possible based on the farm’s financial circumstances.

Future Plans

The next steps are to complete the economic analyses of a total of 60 MMS and integrate these into the decision-support tool. We plan to demonstrate this tool to extension specialists and producers to refine the user interface, key assumptions, functioning of the decision algorithm, and the usability of the results.

Authors

Erin E. Scott, PhD Graduate Assistant, University of Arkansas

Corresponding author email address

erins@uark.edu

Additional authors

Sudharsan Varma Vempalli, Postdoctoral Research Associate, University of Arkansas

Jacob Hickman, Program Coordinator, University of Arkansas

Jennie Popp, Professor, University of Arkansas

Richard Stowell, Professor, University of Nebraska-Lincoln

Teng Lim, Extension Professor, University of Missouri

Greg Thoma, Professor, University of Arkansas

Lauren Greenlee, Associate Professor, Penn State University

Additional Information

Related presentation during this session by Varma et al., titled “A Decision-Support Tool for The Design and Evaluation of Manure Management and Nutrient Reuse in Dairy and Swine Farm Facilities”.

Acknowledgements

We acknowledge funding support from the United States Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA) grant award (# 2018-68011-28691). We would also like to thank our full project team and outside experts for their guidance on this project.

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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Exploring the Effect of a Peptide Additive on Struvite Formation and Morphology: a High-Throughput Method

Purpose

Precipitation of struvite (MgNH4PO4·6H2O), a slow-release fertilizer, provides a means of recycling phosphorus from wastewater streams. In this work, a method for high-throughput struvite precipitation is developed to investigate the effects of a peptide additive.

What Did We Do?

The reactions occurred in small volumes (300 μL or less of magnesium, ammonium, and phosphate solutions) in a 96-well plate for 45 minutes. The formation of struvite was monitored by fitting absorbance at 600 nm over time to a first-order model with induction time. The impact of struvite seed dosing was also investigated, highlighting the importance of optimization when peptide is present. The composition of the precipitate was confirmed through Fourier-transform infrared spectroscopy, while morphology and crystal size were analyzed through optical microscopy. Finally, the utility of the high-throughput platform was demonstrated with a 25 full factorial design to capture the effects and interactions of: magnesium dose, mixing time, seed dose, pH, and temperature.

What Have We Learned?

The addition of peptide induced significant changes to the yield parameter and formation constant in the model. Crystals grown in the presence of peptide were morphologically different, having a higher aspect ratio than crystals grown in the absence of peptide. Controlling the shape of the crystal may impact the dissolution properties of struvite.

Future Plans

We anticipate that the general technique investigated can be applied to more complex water matrices (e.g. wastewater), with purity investigated spectroscopically or through other high-throughput assays. Future work will focus on identifying the mechanism by which the peptide acts. The use of a sequence-defined peptide paves the way for further developments in favorably modifying struvite formation and growth. With the effects of shADP5 documented, other similar peptides can be explored via either computational simulations or experimentation to modulate the quality and yield of struvite – potentially increasing its value as a fertilizer. Further computational studies also need to be explored to elucidate the exact mechanism by which shADP5 modulates the thermodynamics of struvite crystallization.

Authors

Presenting author

Jacob D Hostert, PhD candidate, Case Western Reserve University

Corresponding author

Julie N. Renner, Assistant professor, Case Western Reserve University

Corresponding author email address

Jxr484@case.edu

Additional authors

Olivia Kamlet, undergraduate, Case Western Reserve University

Zihang Su, Postdoctoral scholar, Columbia University

Naomi S. Kane, B.S., Case Western Reserve University

Additional Information

Hostert, J. D.; Kamlet, O.; Su, Z. H.; Kane, N. S.; Renner, J. N. Exploring the effect of a peptide additive on struvite formation and morphology: a high-throughput method. RSC Advances 2020, 10 (64), 39328-39337, Article. DOI: 10.1039/d0ra06637k.

Acknowledgements

This work was supported by the United States Department of Agriculture (Award No. 2018-68011-28691) and the National Science Foundation (Award No. 1739473).

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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Advances in Nutrient Recovery Technology: Approaches to Controlling Recovered Product Chemistry

Purpose

Our recent work has focused on developing approaches to nutrient management and recovery, with a particular focus on using electrochemical and membrane technologies to control the chemistry of the recovered nutrient products. We are interested in being able to recover both ammonia and phosphate, and our goal is to create recycled fertilizer products that can allow the agricultural community to control the ratio of nitrogen to phosphorus in the recycled fertilizer products and to control whether those fertilizer products are in liquid form or in solid form. With the electrochemical technology focus, we see benefits that include no required chemical dosing, scalable reactor design, and the ability to couple to renewable energy sources. Our engineering research on nutrient recovery technology is conducted within a team that includes life cycle assessment, economic analysis, agronomic greenhouse and row crop studies, agricultural sector outreach, and the development of a decision-support tool to help farmers understand technology options for water and nutrient management.

What Did We Do?

We have investigated an electrochemical cell design that includes a magnesium metal anode and a stainless-steel cathode. The corrosion of the magnesium anode results in the release of magnesium cations into solution, and these magnesium cations promote the precipitation of struvite, otherwise known as magnesium ammonium phosphate hexahydrate (Figure 1). We have investigated how operating conditions of the electrochemical cell, including voltage, residence time, batch vs flow, and membrane separation of the two electrodes, affect nutrient recovery efficiency and the overall chemistry of the recovered precipitate. Our studies have included control experiments on synthetic wastewater compositions relevant to hog and dairy farm wastewaters, while we have also conducted laboratory-scale studies on natural wastewater samples from both agricultural and municipal sources. To demonstrate initial scale-up of an electrochemical reactor, we have designed a bench-scale reactor (Figure 2) that is capable of producing kilogram-level batches of struvite.

Figure 2. (a) Bench-scale batch reactor demonstration for kg-level struvite precipitation. (b) One engineering challenge is the precipitation of struvite on the electrode surface.

What Have We Learned?

The production of struvite from an electrochemical reactor can be controlled by the applied voltage and residence time of the wastewater in the reactor. Changes in reactor design, including the inclusion of a membrane to separate the anode and cathode and operation in batch vs flow mode, can change the composition of the struvite precipitate and can cause a change in the balance of struvite formed vs hydrogen gas formed from the electrochemical cell. We are also able to produce K-struvite, a potassium-based alternative to conventional struvite, that includes potassium rather than ammonium, and the production of K-struvite allows the recovery of the phosphate in a particulate fertilizer while also allowing the separation and recovery of ammonia in a separate liquid stream. We have learned that one of the primary challenges to the electrochemical reactor operation is fouling of the electrodes by the struvite precipitate (Figure 2), and we have developed a dynamic voltage control approach that enables minimal electrode fouling and therefore increases struvite recovery and decreases energy consumption. Our energy consumption values are similar to that of chemical precipitation processes that have been developed for nutrient recovery.

Future Plans

Future plans include further development and optimization of the dynamic voltage control approach to electrochemical reactor operation, which will allow us to control electrode fouling. We also plan to continue working with natural wastewater samples and further develop flow cell reactor design to understand how to translate our batch reactor studies to a flow reactor environment. Studies on K-struvite will focus on understanding the kinetics of K-struvite precipitation and the competing reactions (e.g., calcium precipitation and struvite precipitation) that might impact K-struvite recovery.

Authors

Lauren F. Greenlee, Associate Professor, Pennsylvania State University

Corresponding author email address

greenlee@psu.edu

Additional authors

Laszlo Kekedy-Nagy, Postdoctoral Fellow, Concordia University

Ruhi Sultana, Graduate Research Assistant, Pennsylvania State University

Amir Akbari, Graduate Research Assistant, Pennsylvania State University

Ivy Wu, Graduate Research Assistant, Colorado School of Mines

Andrew Herring, Professor, Colorado School of Mines

Additional Information

    1. Kekedy-Nagy, Z. Anari, M. Abolhassani, B.G. Pollet, L.F. Greenlee. Electrochemical Nutrient Removal from Natural Wastewater Sources and its Impact on Water Quality. Water Research (2022), 210, 118001, DOI: 10.1016/j.watres.2021.118001.
    2. Kékedy-Nagy, M. Abolhassani, R. Sultana, Z. Anari, K.R. Brye, B.G. Pollet, L. F. Greenlee. The Effect of Anode Degradation on Energy Demand and Production Efficiency of Electrochemically Precipitated Struvite, Journal of Applied Electrochemistry (2021), DOI: 0.1007/s10800-021-01637-y.
    3. Kékedy-Nagy, M. Abolhassani, S.I. Perez Bakovic, J.P. Moore II, B.G. Pollet, L.F. Greenlee. Electroless Production of Fertilizer (Struvite) and Hydrogen from Synthetic Agricultural Wastewaters, Journal of the American Chemical Society (2020), 142(44), 18844-18858. DOI: /10.1021/jacs.0c07916.
    4. Wu, A. Teymouri, R. Park, L.F. Greenlee, and A.M. Herring. Simultaneous Electrochemical Nutrient Recovery and Hydrogen Generation from Model Wastewater Using a Sacrificial Magnesium Anode, Journal of the Electrochemical Society (2019), 166(16), E576-E583. DOI: 10.1149/2.0561916jes.

Acknowledgements

The authors acknowledge funding from the USDA NIFA AFRI Water for Food Production Systems program, grant #2018-68011-28691 and funding from the National Science Foundation, grant #1739473.

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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Promoting Manure Composting for Livestock Operations

Purpose

While both raw and composted manure benefit soil health and crop production, there are benefits to creating and land-applying composted manure over raw manure. Product uniformity, volume, weed seed, pathogen and parasite reduction and nutrient stability are just a few of the benefits. However, composting manure in Minnesota and North Dakota have yet to gain popularity.

A group of compost producers, who ultimately became our producer cooperators and partnered with us for workshops, were consulted on the reason composting manure is not more common. One said, “It is lack of understanding and time management that holds most other farmers back from composting manure; they do not know how much composting can help their operation.” Another mentioned, “When I started researching composting for my farm, I took a three-day class in Illinois because there wasn’t anything available in North Dakota or Minnesota. Most farmers are not willing to travel that far. There is a need for composting education programs in the two-state area.”

What Did We Do?

NDSU Extension partnered with the University of Minnesota Extension with the original plan of holding four workshops in two years (two each in ND and MN). When implications from the COVID-19 pandemic ensued, we changed our plans to host an online workshop in 2020 and were able to continue with two in-person workshops in 2021.

The online workshop consisted of 13 videos that were sent to registrants 2 weeks before an online, live discussion was held in August 2020 with the presentation team as well as 3 producer cooperators. One of the videos consisted of on-farm interviews with each of our producer cooperators to show the registrants the ability to manage compost differently with similar results. The videos are still available and have been viewed collectively 1,845 times.

The in-person workshops were held in July and August of 2021. Each workshop covered the same material as the online workshop and all three producer cooperators attended each event. The producer cooperators were responsible for helping attendees with the compost diagnostics activity as well as answering questions during a panel discussion.

What Have We Learned?

Online Workshop

    • 180 people registered for the online workshop and 50 joined the live discussion with presenters and producer cooperators
    • 43 responded to the immediate follow-up survey where
      • 76% thought the self-paced format was excellent
      • 64% thought the amount of material was excellent
      • 62% thought the topics covered were excellent
    • 15 months after the online workshop, 21 people participated in a follow-up survey and as a result of the workshop, 58% reported they had altered their manure composting practices.
    • When asked what manure composting change(s) they made, 58% reported they improved their operations adding,
      • “I have more confidence in my ability to compost successfully and have a better understanding of the environmental impacts of composting.”
      • “I no longer have to pay someone to haul away our waste”
      • “Although not composting on a commercial level, I manage several community gardens where large volumes of biomass are accumulated. After learning additional techniques, my piles were hotter and decomposed more quickly. The key? More moisture!”

Moving the workshop online for the first year allowed us to fully engage our producer cooperators. The online workshop resulted in participant comments such as,

    • “Well organized and executed. Appreciated that videos were individual by topic area, short, and focused. That allowed me to watch what was relevant and fit it into my day more easily.”
    • “Really enjoyed the discussion and interaction between the three cooperators. Also appreciated having enough time to flesh out the information, i.e., didn’t try to squeeze it into one hour.”

Though an in-person meeting would have allowed more hands-on experience, the online version reached a broader audience with attendees from 31 states and 3 countries.

In-person Workshops

    • 31 people attended the in-person workshops in ND and MN, of which 10 participated in a 4-month follow-up survey
      • 67% of those who made changes as a result of the workshop stated they started composting manure
    • 100% of those who did not make changes were either agency or university Extension/research personnel who reported the workshops impacted them, their work, and/or their relationship with their clients by:
      • “Allowing me to be more educated about manure composting so that when producers inquire about composting I am able to give them accurate information.”
      • “Using workshop information to inform clients of another manure handling method to consider; composting.”

The workshops, both online and in-person, facilitated discussion and mutual learning among experienced and novice composters of livestock manure.

Future Plans

Questions about static composting were asked during both the online and in-person workshops. This practice is not common in North Dakota or Minnesota so there is certainly a future learning and workshop opportunity.

Authors

Mary A. Keena, Extension Specialist, North Dakota State University

Corresponding author email address

mary.keena@ndsu.edu

Additional authors

Chryseis Modderman, Extension Educator, University of Minnesota; Melissa L. Wilson, Assistant Professor and Extension Specialist, University of Minnesota; William J. Gale, Extension Agent, North Dakota State University

Additional Information

    1. Online Composting Workshop Videos YouTube playlist: https://youtube.com/playlist?list=PLnn8HanJ32l6uhwdS9m-G1z8Bq1U0aJzF
    1. Two compost-related publications for producers were created for use while at the compost rows:

Acknowledgements

This project was funded by North Central Sustainable Agriculture Research and Education (NC-SARE).

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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Assessment of physical properties for cover crop and manure applied soils in Idaho’s Magic Valley

Purpose

Idaho ranks in the top 10 in the US for dairy, potato, barley, hay, sugarbeet, corn silage, and dry bean production with the highest producing area being in South Central Idaho. Crop and livestock producers in the Magic Valley depend on affordable access to clean water, healthy and productive soils, and quality grazing land to remain profitable. However, portions of the Middle Snake River, which provides irrigation and drinking water to the Magic Valley, have been impaired by high phosphorous and sediment loading for over two decades (Tetra Tech, 2014). To measure progress in producer efforts for reducing erosion and runoff, appropriate methods need identified. The soils in this region are prone to crusting, have low organic matter, and are high in calcium carbonates making these soils unique to much of the United States. Thus, the overall goal of this project was to identify management practices that enhance soil health physical properties in the Magic Valley.

What Did We Do?

Two study sites were located on the USDA-ARS Northwest Irrigation & Soils Research Laboratory farm in Kimberly, Idaho, and were established in 2013 (Long-Term Manure) and 2016 (Cover Crop). Long-Term Manure was set up as a randomized complete block design with four replicates and eight treatments. The treatments are as follows: annual application of solid dairy manure at rates of (i) 10, (ii) 20, and (iii) 30 ton per acre(dry weight), biennial application of solid dairy manure at rates of (iv) 10, (v) 20, and (vi) 30 ton per acre (dry weight), (vii) application of inorganic fertilizer (applied to match manure N and P rates; Fert), and (viii) no amendments (Control). A commercial crop rotation of wheat-potato-barley-sugarbeet was used at this study site, and sampling occurred under sugarbeet in 2020. All plots were disked immediately after manure application, and all plots were moldboard plowed prior to sugarbeet and potato planting. The Cover Crop study was set up as a split plot design with four replications and tillage as the main experimental factor (strip till vs disk/chisel plow). The four sub-treatments are as follows: (a) no cover crop or dairy manure (Control), (b) cover crop only (CC only), (c) manure only (M only), and (d) cover crop with manure (CC + M). Treatments that did not receive manure received inorganic fertilizer to meet recommended crop needs based on spring soil tests. Inorganic fertilizer was only applied to manure treatments if spring soil tests indicated that additional nutrients were required and the manure did not meet the crop needs. From 2016 to 2021, the field was cropped with continuous silage corn. Triticale was used as a winter forage cover crop and was planted directly after manure application and was harvested within one week of corn planting. Stockpiled dairy manure was applied at a rate of 30 ton per acre (dry weight) in the fall after corn silage harvest and incorporated by disking or left on the surface.

The physical properties accessed for each study in late summer 2020 were soil aggregate stability, runoff rate and rainfall before runoff, bulk density, and compaction. Two methods were used to measure soil aggregate stability: wet sieving and a hybrid method utilizing a Cornell Sprinkle Infiltrometer (CSI). The wet sieving method incorporated four nested stainless steel wire sieves at particle diameters of 5/32, 5/64, 1/64, and 0.002 inch. The samples were submerged in 9.5 inch of water oscillating up and down 1.5 inch at 30 oscillations per minute for 10 minutes. A CSI was used to measure soil aggregate stability at the heights of 1, 3, and 5 feet. The CSI operated at a constant rainfall rate of 0.79 inch of rainfall per 10 min of operation. Runoff rate and rainfall before runoff were calculated based on the values collected from the CSI using the equations listed in van Es and Schindelbeck (2001). The CSI was placed on top of a metal ring (9.5 inch diameter), and a runoff tube was fitted in the metal ring to measure runoff. The CSI had an air entry of 3.9 inch, and data was recorded every 2 minutes once runoff started to occur until the outflow reached steady state. Because each measurement took a minimum of one hour, only one block was measured each day for a total of four days. Bulk density measurements were taken at depths of 0-2, 2-4, and 4-6 inch at each plot. Compaction was measured using a penetrometer to measure a total depth of 12 inch at increments of 1 inch.

What Have We Learned?

Two methods (wet sieving and CSI hybrid) were compared for accessing soil aggregate stability among the two studies. No differences in aggregate stability were found when the wet sieving method was used among treatments for both studies (Figure 1). However, the CSI hybrid method was found to be statistically different at an operational height of 1 foot among treatments at mean values of 0.147 ± 0.005 inch (CC + M), 0.145 ± 0.005 inch(CC only), and 0.146 ± 0.005 inch (M only) as compared to the control (0.124 ± 0.005 inch) for the Cover Crop study. It is also clear that there are large numerical differences in mean weight diameters between the operational heights for the Cover Crop study.

Figure 1. The mean weight diameter (MWD) at the Long-Term Manure (A, B) and Cover Crop (C, D) study sites. A and C represent MWD using the traditional wet sieving method, and B and D represent MWD using the Cornell Sprinkle Infiltrometer at 1, 3, and 5 foot. At the Long-Term Manure study site, 10A, 20A, and 30A represents plots that received dairy manure annually (ton per acre), and 10B, 20B, and 30B represents plots that received dairy manure biennially (ton per acre). Bars represent mean plus standard error. Columns within years not connected by the same letter are significantly different (p<0.05).

 

Significant differences in rainfall before runoff were found between treatments in the Cover Crop study, and the mean values were 2.26 ± 0.23 in (CC + M), 1.70 ± 0.23 in (CC only), and 1.53 ± 0.23 in (M only) when compared to the control (1.45 ± 0.23 in) (Figure 2). No differences were found in the Long-Term Manure study. When measuring bulk density, it was found that measurements at the 0–2-inch depth were found to be statically significant (p≤0.05) with means of 52.7 ± 3.7 pound per cubic foot (CC + M), 59.6 ± 3.7 pound per cubic foot (CC only), and 49.4 ± 3.7 pound per cubic foot (M only) when compared to the control (65.9 ± 3.7  pound per cubic foot), respectively. Compaction was found to be statistically significant at the depths of 1 through 4 inch and 10 and 12 inches. The tillage by treatment effect was also found to be statistically significant at 2 and 3 inches. Assessing physical properties among management practices can give producers a clearer insight into soil health in the Magic Valley.

Figure 2. The average runoff rate and rainfall before runoff at the Long-Term Manure (A, B) and Cover Crop (C, D) study sites. At the Long-Term Manure study site, 10A, 20A, and 30A represents plots that received dairy manure annually (ton per acre), and 10B, 20B, and 30B represents plots that received dairy manure biennially (ton per acre). Bars represent mean plus standard error. Columns within years not connected by the same letter are significantly different (p<0.05).

Future Plans

At the Long-Term Manure study site, dairy manure was applied annually or biannually from 2013-2019. The project now focuses on nutrient drawdown and manure will no longer be applied. Cover crops may be incorporated into the project. At the Cover Crop study site, inversion tillage will be performed spring of 2022 prior to planting silage corn to incorporate the dairy manure into the topsoil. Dairy manure has not been applied to the field since fall of 2020. Inorganic fertilizer will be applied if needed.

Authors

Presenting author

Kevin Kruger, Research Support Scientist, University of Idaho

Corresponding author

Linda R. Schott, Nutrient and Waste Management Extension Specialist, University of Idaho

Corresponding author email address

lschott@uidaho.edu

Additional authors

Jenifer L. Yost, Research Soil Scientist, USDA-ARS; April B. Leytem, Research Soil Scientist, USDA-ARS; Robert S. Dungan, Research Microbiologist, USDA-ARS; Amber D. Moore, Soil Fertility Specialist, Oregon State University

Additional Information

Part of this research was presented at the ASA, CSSA, SSSA International Annual Meeting in Salt Lake City, Utah, in November of 2021. The link to the recorded presentation is found in the citation below:

Yost, J.L., Kruger, K., Leytem, A.B., Dungan, R.S., & Schott, L.R. (2021). Measuring Soil Aggregate Stability Using Three Methods in Aridisols Under Continuous Corn in Southern Idaho [Abstract]. ASA, CSSA, SSSA International Annual Meeting, Salt Lake City, UT.

https://scisoc.confex.com/scisoc/2021am/meetingapp.cgi/Paper/138171

More information about the Long-Term Manure project can be found in the following scientific papers:

Leytem, A.B., Moore, A.D., & Dungan, R.S. (2019). Greenhouse gas emissions from an irrigated crop rotation utilizing dairy manure. Soil Science Society of America Journal, 83, 137-152.

https://eprints.nwisrl.ars.usda.gov/id/eprint/1693/

Bierer, A.M., Leytem, A.B., Dungan, R.S., Moore, A.D., & Bjorneberg, D.L. (2021). Soil organic carbon dynamics in semi-arid irrigated cropping systems. Agronomy, 11, 484.

https://doi.org/10.3390/agronomy11030484

The papers that were referenced in this proceedings paper are:

Reynolds, W. D., & Elrick, D. E. (1990). Ponded infiltration from a single ring: I. Analysis of steady flow. Soil Science Society of America Journal, 54, 1233–1241.

https://doi.org/10.2136/sssaj1990.03615995005400050006x.

Tetra Tech. (2014). Reevaluation of Mid Snake/Upper Snake-Rock Subbasin TMDL: Data Summary, Evaluation, and Assessment.

van Es, H. & Schindelbeck, R. (2001). Field Procedures and Data Analysis for the Cornell Sprinkler Infiltrometer. Department of Crop and Soil Science Research Series R03-01. Cornell University.

Acknowledgements

This project was funded by a USDA ARS Cooperative Agreement and USDA NIFA Project Number IDA01657. The authors would like to thank Emerson Kemper for assisting with the lab work and Peiyao Chen for assisting with field work.

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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Impact of swine manure on soil health properties: A systematic review

Purpose

As the campaign to improve agricultural soil health has gained momentum among conservationists and researchers worldwide, a comprehensive assemblage of outcomes from manure and soil health-related research studies is important. Particularly, the identification of knowledge gaps is an important step to direct future research that informs soil health improvement outreach programs. A thorough review of data reporting the effects of swine manure on soil health properties that is applicable to agricultural producers is lacking. Although previous research studies have looked at the effects of manure on individual soil properties, there are conflicting conclusions. Livestock manure literature reviews fail to consider inconsistent methodologies between individual research studies and whether research is applicable to producers utilizing manure as amendments to improve soil health, and none of the reviews focus on swine manure or swine manure by-products. The objectives of this review were (a) to synthesize literature describing effects of swine manure on soil properties that affect soil health and (b) to identify knowledge gaps and research needs to further our understanding of this topic.

What Did We Do?

We conducted a systematic literature review based on peer-reviewed studies that evaluated the effect of swine manure on soil health properties. First, we identified studies using three criteria: species (swine, pig, hog), manure source (i.e., solid [SM] or liquid manure [LSM], compost, deep pack), and soil property (i.e., soil organic carbon [SOC], total nitrogen, soil pH, bulk density, available water capacity). Second, studies had to meet the following criteria in order to be included: (a) the studies were replicated field experiments, (b) manure was the only differing factor between or among treatments, and (c) data means of organically amended treatments and controls were included. In total, 40 peer-reviewed studies were included in this review.

What Have We Learned?

Recycling of manure locally prior to importing inorganic fertilizer (IF) has the potential to reduce nutrient imbalances and improve soil health. Based on this review, swine manure has the potential to add significant amounts of organic carbon to the soil and to improve soil health metrics. In general, the application of swine manure increases soil organic matter (SOM) and SOC, decreases soil bulk density, and increases microbial biomass carbon Soil organic carbon and total N tended to be highest when manure and inorganic fertilizer were applied to the field (Figure 1). Soil chemical properties did not seem to change much when manure was applied to the soil surface or incorporated into the topsoil. The duration of swine manure application (annually) did not seem to increase the percent change in most chemical properties; however, this could be due to a lack of data. The percent change in SOC did increase when the swine manure was applied for a longer time period (Figure 1), and we would expect to see a similar trend with SOM and total carbon if there were more data. Few articles had data on soil physical and biological properties. Depending on soil type, swine manure has the potential to increase available water holding capacity and saturated hydraulic conductivity. Although more research is needed, it can be inferred that swine manure additions increase microbial activity, which promotes healthier soils and better crop yields.

Figure 1: Average percent change in soil organic carbon (SOC) and total nitrogen (TN) based on amendment type, application method, soil texture, and duration of swine manure application. Black circles represent outlier data, and diamonds represent mean. IF = inorganic fertilizer; LSM = liquid swine manure; M + IF = manure (liquid and solid) plus inorganic fertilizer; SM = solid swine manure

Future Plans

Previous literature reviews failed to account for differences in methodologies between individual research studies and whether research is applicable to producers utilizing swine manure as amendments to improve soil health (i.e., unreasonable application rates of swine manure, overapplication of nutrients). The evaluation of the effect of swine manure on soil health properties is difficult to do based on current literature because (a) there are few comprehensive studies (i.e., only one study reported properties from chemical, physical, and biological categories) and (b) there are non-consistent research methodologies between studies. Therefore, we recommend redirecting research studies to demonstrate the value of manure to the suitability of agricultural cropping systems. Future swine manure research should include (a) a range of soil physical, chemical, and biological properties, (b) initial soil data prior to manure application, and (c) manure type, application method, application rate, total carbon and nitrogen of the manure, duration of swine manure application, and swine manure application timing. In addition, future research should also focus on the short- and long-term effects of a single application of manure to support an effort to identify optimal frequency of application for improving soil health. More research is also needed to compare the effects of manure and inorganic fertilizer additions on crop yield and soil health by balancing nitrogen, phosphorus, and potassium additions.

Authors

Jenifer L. Yost, Research Soil Scientist, USDA-ARS

Corresponding author email address

jenifer.yost@usda.gov

Additional authors

Amy M. Schmidt, Livestock Manure Management Engineer, University of Nebraska-Lincoln; Rick Koelsch, Livestock and Bio Environmental Engineer, University of Nebraska-Lincoln; Kevin Kruger, Research Support Scientist, University of Idaho; Linda R. Schott, Nutrient and Waste Management Extension Specialist, University of Idaho

Additional Information

For more information about this project, please check out our Open Access journal article. The citation for the journal article is:

Yost, J.L., Schmidt, A.M., Koelsch, R., and Schott, L.R. (2022). Effect of swine manure on soil health properties: A systematic review. Soil Science Society of America Journal.

https://doi.org/10.1002/saj2.20359

This research was presented at the ASA, CSSA, SSSA International Annual Meeting in Salt Lake City, Utah, in November of 2021. The link to the recorded presentation is found in the citation below:

Yost, J. L., Schmidt, A. M., Koelsch, R., & Schott, L. R. (2021). Impact of Swine Manure on Soil Health Properties: A Systematic Review [Abstract]. ASA, CSSA, SSSA International Annual Meeting, Salt Lake City, UT. https://scisoc.confex.com/scisoc/2021am/meetingapp.cgi/Paper/138180

Acknowledgements

This project was supported by funding from the National Pork Checkoff. The authors would also like to thank Meg Clancy and Drew Weaver for their assistance.

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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The Manure Analysis Proficiency Program: Trends in laboratory manure testing methods

Purpose

The Manure Analysis Proficiency (MAP) Program, administered by the Minnesota Department of Agriculture, began in the mid-1990s to assist US Midwest analytical laboratories to verify the accuracy (including both bias and precision) of laboratory manure analyses. In 2003, the program expanded nationally and continues today. With an annual enrollment of 60 to 74 labs each year over the past two decades and the analysis of 120 manure proficiency samples of 12 test parameters, trends in laboratory methods and performance have arisen. The presentation will cover inter-laboratory bias and precision of the primary manure analysis parameters: total solid content, nitrogen, ammonia nitrogen (NH3-N), phosphorus and potassium.

What Did We Do?

The MAP Program was designed to follow international standards under the ISO/IEC 17025 general requirements for the coordination of a proficiency testing program. This includes development and use of standard protocols for the preparation of manure proficiency testing (PT) samples, the use of blind sample replicates for the assessment of intra-lab precision, and the implementation of robust statistical measures for the assessment of data for the evaluation of both laboratory accuracy (bias) and precision.

Since 2002, the MAP program has sent PT samples to laboratories twice per year. Each cycle includes three manure types with each type having three replicates (for a total of nine manure samples). The PT samples are selected based on source animal type and a range of total solids (2-90%). Samples are thoroughly ground and homogenized and then packaged and frozen prior to overnight shipping to program participants. Each participating laboratory completes the required tests and sends back their results along with their analytical methods used to the MAP program. With the results tabulated from all laboratories each cycle, method bias is assessed based on the inter-lab (or between lab) median and 95% confidence limits (using the median absolute deviation). Precision is assessed based on the intra-lab (or within lab) relative standard deviation of PT sample replicates. Participating labs are provided graphical reports illustrating method performance as well as lab bias and precision.

One-hundred twenty-nine manure PT samples from dairy, beef, swine, and poultry operations have been evaluated since 2002 and each sample was analyzed by 60 to 74 labs participating in the MAP program (depending on the year). The samples ranged from 3.1 to 91% total solids, 0.02 to 2.71% total nitrogen, and 0.05 to 0.48% total phosphorus. With this wide range of manure types and conditions, plus the ability to pair data with manure analysis methods and accuracy ratings, we can evaluate the efficacy of certain methods and discuss their pros and cons.

What Have We Learned?

MAP program results for nitrogen have shown the dry combustion method to be unsuitable for manure samples with total solid content less than 10%. Results for four different ammonia methods indicate generally good agreement between methods in the median concentrations, but methods varied in precision. Across samples, intra-laboratory precision decreased with decreasing analyte concentration, often associated with decreased manure total solid content. In general, total solids, phosphorus and potassium methods were of high precision with intra-lab precision < 5%. Manure test parameters exhibiting poor intra-lab precision were EC, pH, and NO3-N.

Future Plans

The MAP program continues to operate under the Minnesota Department of Agriculture in partnership with Central Lakes College in Brainerd, MN. The team is currently working with the USDA-NRCS (who provided funding), the University of Minnesota, and laboratory directors of public and private laboratories to update the “Recommended Methods of Manure Analysis” manual which is expected to be released and printed in 2022.

Authors

Robert Miller, Technical Director, Agricultural Laboratory Proficiency Program

Corresponding author email address

rmiller@soiltesting.us

Additional author

Jerry Floren, MAP Program Director (retired), Minnesota Department of Agriculture

Additional Information

https://www.mda.state.mn.us/pesticide-fertilizer/certified-testing-laboratories-manure-soil

Acknowledgements

Larry Gunderson at the Minnesota Department of Agriculture

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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Trends in Manure Sample Data

Purpose

Most manure book values used today from the MidWest Plan Service (MWPS) and American Society of Agricultural and Biological Engineers (ASABE) were derived from manure samples prior to 2003. To update these manure test values, the University of Minnesota in partnership with the Minnesota Supercomputing Institute, is working to build a dynamic manure test database called ManureDB. During this database construction, the University of Minnesota collected manure data spanning the last decade from five labs across the country. Trends, similarities, and challenges arose when comparing these samples. Having current manure test numbers will assist in more accurate nutrient management planning, manure storage design, manure land application, and serve agricultural modeling purposes.

What Did We Do?

We recruited five laboratories for this preliminary study who shared some of their manure sample data between 2012-2021, which represented over 100,000 manure samples. We looked at what species, manure types (liquid/solid), labels, and units we had to work with between the datasets to make them comparable. Once all the samples were converted into either pounds of nutrient/ton for solid manure or pounds of nutrient/1000 gallons for liquid manure, we took the medians of total nitrogen, ammonium-nitrogen (NH4-N), phosphate (P2O5), and potassium oxide (K2O) analyses from those samples and compared them to the MWPS and ASABE manure nutrient values.

What Have We Learned?

There is no standardization of laboratory submission forms for manure samples. The majority of samples have minimal descriptions beyond species of animal and little is known about storage types. With that said, we can still detect some general NPK trends for the beef, dairy, swine, poultry manure collected from the five laboratories in the last decade, compared to the published book values. For liquid manure, the K2O levels generally increased in both the swine and poultry liquid manure samples. For the solid swine manure and solid beef manure, total N, P2O5, and K2O levels all increased compared to the published book values. The solid dairy manure increased in P2O5 and K2O levels, and the solid poultry manure increased in total N and K2O. See Figure 1 for the general trends in liquid and solid manure for swine, dairy, beef, and poultry.

Table 1. Manure sample trends 2012-2021 compared to MWPS/ASABE manure book values. (+) = trending higher, (o) = no change/conflicting samples, (-) = trending lower

Liquid Total N NH4–N P2O5 K2O
Swine o o – +
Dairy – o – o
Beef o o o o
Poultry o + – +
Solid Total N NH4–N P2O5 K2O
Swine + o + +
Dairy o o + +
Beef + – + +
Poultry + o o +

Future Plans

The initial data gives us a framework to standardize fields for the future incoming samples (location, manure type, agitation, species, bedding, storage type, and analytical method) along with creating a unit conversion mechanism for data uploads. We plan to recruit more laboratories to participate in the ManureDB project and acquire more sample datasets. We will compare and analyze this data as it becomes available, especially more detailed data for each species. We will be designing ManureDB with statistical and data visualization features for future public use.

Authors

Nancy L. Bohl Bormann, Graduate Research Assistant, University of Minnesota

Corresponding author email address

bohlb001@umn.edu

Additional authors

Melissa L. Wilson, Assistant Professor, University of Minnesota

Erin L. Cortus, Associate Professor and Extension Engineer, University of Minnesota

Kevin Janni, Extension Engineer, University of Minnesota

Larry Gunderson, Pesticide & Fertilizer Management, Minnesota Department of Agriculture

Tom Prather, Senior Software Developer, University of Minnesota

Kevin Silverstein, Scientific Lead RIS Informatics Analyst, University of Minnesota

Additional Information

ManureDB website: http://manuredb.umn.edu/ (coming soon!)

Twitter: @ManureProf, @nlbb

Lab websites:

https://wilsonlab.cfans.umn.edu/

https://bbe.umn.edu/people/erin-cortus

Acknowledgements

This work is supported by the AFRI Foundational and Applied Science Program [grant no. 2020-67021-32465] from the USDA National Institute of Food and Agriculture, the University of Minnesota College of Food, Agricultural and Natural Resource Sciences, and the Minnesota Supercomputing Institute.

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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Dynamic manure “book values” through the U.S. National Manure Database

Purpose

Most manure composition data summaries available in the U.S. are outdated because genetics, feed rations, manure handling, and housing practices have evolved over the past two decades. This means that the community that uses this manure data, such as farmers developing manure management plans, engineers designing manure storages, state and federal regulators establishing best management practices for manure land application, or researchers modeling nutrient cycling and gas emissions, is using outdated information. Thousands of manure samples, however, are analyzed every year by university and commercial labs across the country and could provide an up-to-date source of information. Until recently, there has been no mechanism for combining and summarizing this valuable data in a way that makes the results accessible to the broader community of users. Together with the Minnesota Supercomputing Institute (MSI) and the Minnesota Department of Agriculture (MDA) – who runs the only manure analysis proficiency program in the United States – researchers at the University of Minnesota are developing a national database for manure test results. The database, or ManureDB, will meet FAIR principles (Findable, Accessible, Interoperable, and Reusable) to ensure the data is shared and used by a wide audience.

What Did We Do?

The project team brought together a stakeholder group involved with manure management, regulation, lab analysis, and research to help us develop standards and best practices for data management. The stakeholder team helped inform the creation of several deliverables to date, including a schema and framework for the database, as well as a data use agreement template. The MSI is currently working on the development of the public-facing website that will interface with the database as well as a data cleaning tool to help standardize the data as it is uploaded.

What Have We Learned?

The stakeholder group identified that data privacy is a top priority. Customer data (i.e., name and address) will be removed, though state and zip codes will remain with the data (full zip codes will not be shared publicly). We also found that there is a stark difference between what data the full stakeholder team would like to see (i.e., manure data for livestock facilities by county or watershed code for different livestock species and manure storage types) versus what commercial laboratories collect (i.e. livestock species and sometimes the address of the livestock facility, but more often the address of the person requesting the tests). Standardizing manure submission forms in the future will potentially help ensure that information collected for each sample is consistent. Future educational efforts for those advising farmers on manure testing will be needed to ensure the forms are filled out accurately instead of being left blank.

Future Plans

This project is ongoing. We are in the process of working with our current participating labs to sign data use agreements and then to clean and upload data. New labs will be recruited throughout the project period. A public-facing dashboard will be created to search through aggregate data. We are working with our stakeholder groups to design websites for other potential use cases, including a site to download cleaned data for research purposes and potentially a site for labs to be able to benchmark their samples against labs from within and outside of their regions.

Authors

Melissa L. Wilson, Assistant Professor and Extension Specialist, University of Minnesota

Corresponding author email address

mlw@umn.edu

Additional authors

Erin L. Cortus, Associate Professor and Extension Engineer, University of Minnesota

Nancy L. Bohl Bormann, Graduate Research Assistant, University of Minnesota

Kevin Janni, Extension Engineer, University of Minnesota

Larry Gunderson, Pesticide & Fertilizer Management, Minnesota Department of Agriculture

Tom Prather, Senior Software Developer, University of Minnesota

Kevin Silverstein, Scientific Lead RIS Informatics Analyst, University of Minnesota

Additional Information

Manuredb.umn.edu (coming soon)

Acknowledgements

This work is supported by the AFRI Foundational and Applied Science Program [grant no. 2020-67021-32465] from the USDA National Institute of Food and Agriculture. We’d also like to thank our stakeholders for their time commitment.

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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