Impact of Fluctuating Fertilizer Prices on Poultry Manure Nutrient Value

Over the last 15 years it has become common to build new poultry production facilities on a piece of property that will provide the necessary land area for all of the barns and support facilities, and that comply with the setbacks (i.e. surface water, nearest neighbors) required by local, state, and federal regulations. The manure management plan in such cases depended on the transport of poultry manure to remote cropland that was often not owned and managed by the poultry producer. In some states, the law held the poultry producer legally responsible for any possible environmental consequences associated with irresponsible spreading or handling. Such laws tended to limit transport distances due to the lack of liability transfer.  In other states, like South Carolina, poultry manure brokers were required to have a state permit that allowed for the transfer of liability from the producer to the broker by means of a contract. The broker became liable for proper application rates, adherence to setback requirements, application at agronomic rates, and other state requirements. While transfer of liability did encourage the movement of manure from nearby fields with high soil-test phosphorous contents to remote fields that could benefit from all plant nutrients in manure it also gave rise to an increase in the number or farms that were permitted with manure brokerage as the only manure nutrient management alternative.

During the period from 2002 to 2008 when many new poultry farms were being built the average prices of N, P2O5, and K2O were increasing due to surges in fuel prices. Nitrogen prices increased in a linear manner from 29 to 75 cents per pound or a 2.6 fold increase in price (Table 1 and Figure 1). Prices of the other major nutrients, P2O5 and K2O, increased by over a factor of 3 for the same six year period (Figure 2). Such increases in the cost of fertilizers greatly increased demand for poultry manure, and further encouraged poultry producers to build barns that depended on brokerage as the only manure management option without any considerations of potential decreases in manure value. In recent years, fertilizer prices have decreased and brokerage of manure is not as attractive. The objective of this study was to determine the impact of fertilizer price fluctuations on the value of broiler litter, high-rise layer manure, turkey grow-out litter, and turkey brooder litter.

Table 1. Fertilizer composition information and equation used to convert price per ton to price per pound.
Fertilizer Description Nutrient Content Per Ton of Fertilizer
Urea – 46% N by weight 920 lb N/ton
Ammonium Nitrate – 34% N by weight 680 lb N/ton
Ammonium Sulfate – 21% N and 24% by weight 420 lb N/ton
Conc. Super-Phosphate – 46% P2O5 by weight 920 lb P2O5 /ton
Potassium Chloride – 60% K2O by weight 1200 K2O / ton
Equation Used to Convert Fertilizer Price to Price per Pound of Nutrient $ / lb Nutrient = $ / Ton of Fertilizer÷ lb Nutrient / Ton
Figure 1. Variation in nitrogen prices based on national averages from 2000 to 2012 (USDA-ERS, 2013).
Figure 1. Variation in nitrogen prices based on national averages from 2000 to 2012 (USDA-ERS, 2013).
Figure 2. Variation in P2O5 and K2O prices based on national averages from 2000 to 2012 (USDA-ERS, 2013).
Figure 2. Variation in P2O5 and K2O prices based on national averages from 2000 to 2012 (USDA-ERS, 2013).

What did we do?

Fertilizer Nutrient Content of Poultry Manure

The type of poultry raised in a building and the amount of bedding used causes a wide variation in the plant nutrient content of the manure removed from the building. The manure composition used in the study was taken from data obtained in South Carolina and is shown in Table 2. Broiler litter and turkey grow-out litter were the most similar since pine shavings were used as bedding and several flocks of birds were grown-out on the litter prior to building clean-out. Clean-out frequency varies greatly from every 1 to 1.5 years. The data shown in Table 2 corresponded to annual litter clean-out. The moisture contents (MC) of these two litters were also similar (24% for the broiler litter and 26% for the turkey grow-out litter).  Turkey production begins on a brooder farm where chicks are placed, brooded, and the poults are transported to a grow-out farm. These farms are unique in that the litter was completely changed after each flock. The result is that litter from a brooder farm is much drier (14% moisture content) and contains less manure than any other type of poultry manure. The lower manure content also resulted in lower plant nutrient content. Manure from a high-rise layer barn was at the other extreme. Since no bedding was added to the manure the moisture content was much higher (47%). The high moisture content resulted in lower plant available nitrogen (PAN) content as compared to broiler litter, as well as lower phosphorus content (expressed as P2O5) and potassium (expressed as K2O).

Table 2. Poultry manure composition (lb / ton) used in the analysis (Chastain et al, 2001).
Nutrient Broiler Litter(MC = 24%) Layer Manure(MC = 47%) Turkey Grow-out Litter (MC = 26%) Turkey Brooder Litter (MC = 14%)
Ammonium-N 10 12 12 2.6
Nitrate-N 3.6 None detected 0.4 0.6
Org-N 43.8 22 42 37.2
Total-N 57.4 34 54 40.4
PAN – inc * 38 23 35 25
P2O5 66 51 64 29
K2O 57 26 37 20
* PAN – inc. = Incorporated plant available N = 0.60 x Org-N + 0.80 x Ammonium-N + Nitrate-N

Data for all three forms of nitrogen are provided in Table 2. However, not all of the nitrogen in manure is available for use by a crop. For this study, it was assumed that poultry manure was incorporated on the same day that it was applied by disking. As a result, 80% of the ammonium-N was counted as plant available. The amount of organic-N (Org-N) mineralized was assumed to be 60% based on common recommendations in South Carolina, however mineralization rates vary based on soil temperature, pH, and moisture. All the small amounts of nitrate contained in the manure was counted as available. The equation used for PAN estimates is provided with the table. Additional information concerning the estimate of plant available-N is provided by Chastain et al (2001).

The three plant nutrients used in our analysis are shown in bold colors in Table 2 for each type of poultry manure. They were the PAN, which is the best estimate of the nitrogen in manure that can be substituted for fertilizer-N, P2O5, and K2O.

Fertilizer Component Prices Used

The price of a pound of fertilizer nitrogen depends of the source. The price data shown previously in Figure 1 shows clearly that the most expensive source of nitrogen was ammonium sulfate, followed by ammonium-nitrate and urea. Ammonium-sulfate, the most expensive source of N, has few advantages unless soil-test results indicate that addition of large amounts of sulfur is needed. Ammonium-nitrate is one of the most common types of nitrogen used to manufacture complete fertilizers. It has the advantage of being water soluble, and is not as readily lost to the air as ammonia as compared to urea. Urea has the advantages of being more water soluble than ammonium-nitrate, and contains 35% more N per ton than ammonium-nitrate. The primary disadvantage of urea is that a significant amount (20% to 40%) can be lost to the air by ammonia volatilization unless it is incorporated in the soil to a depth of at least one inch. So the basic question to decide is: which N-price should be used to define the value of the plant available-N in poultry manure? The price of urea was selected because urea and poultry manure behave similarly with regards to ammonia volatilization losses.

The prices of N, P2O5, and K2O were shown to fluctuate widely from 2000 to 2012 (see Figures 1 and 2). The largest cause of these price fluctuations was the price of energy (i.e. oil) needed to manufacture and transport fertilizers. As a result, the prices of these three major plant nutrients were not allowed to vary independently in the analysis. That is, prices of all three nutrients had to be selected by year because of the dependence of all three on energy prices.

It was not a study objective to try to predict future prices since that would be possible, nor was it to perform calculations for each year. To do so would provide many numbers, but would obscure the basic points to be learned. Instead, the approach used was to select nutrient prices by year and use the years that encompassed the linear increase that began in 2004 as well as major peaks and valleys seen in the price of nitrogen in 2008, 2010, and 2012. Prices were also obtained from market reports to obtain prices for the fourth quarter of 2016 (USDA-SC, 2016; DTN, 2016). The actual prices used by year for the analysis are given in Table 3.

Table 3. Component fertilizer prices used in the analysis (USDA-ERS, 2013). The prices shown for 2016 were average prices obtained from market publications from the fourth quarter (USDA-SC, 2016; DTN, 2016).
Year $/lb N (Urea) $/lb P2O5 $/lb K2O
2004 0.30 0.29 0.15
2008 0.60 0.87 0.47
2010 0.49 0.55 0.43
2012 0.60 0.72 0.54
2016 0.37 0.26 0.27

Value of Poultry Manure Used as a Complete Fertilizer – N,P, and K

The first step in the study was to calculate the value of a ton of poultry manure by multiplying the price of N, P2O5, and K2O for each year (Table 3) by the amount of these nutrients per ton of manure (Table 2). This assumes that all of the nutrients in the manure can be used to grow a marketable crop. This is only true if the soil is poor in fertility or the excess P can be used by other crops in the rotation without application of additional manure. Many brokerage contracts in South Carolina, are based on application of 2 tons of litter per acre prior to a primary crop, such as corn or cotton. Additional litter is not spread on the second crop which is often soybeans. The results for the first step are provided in Table 4.

Table 4. Variation in the value of various types of poultry manure ($/ton) based on variability in price of N, P2O5, and K2O. Prices assume that all of the nutrients in the manure can be used in a crop rotation.
Year Broiler (MC = 24%) Layer (MC = 47%) Turkey Grow-out (MC = 26%) Turkey Brooder (MC = 14%)
2004 39.09 25.59 34.61 18.91*
2008 107.01 70.39 94.07 49.63
2010 79.43 50.50 68.26 36.80
2012 101.10 64.56 87.06 46.68
2016 46.61 28.79 39.58 22.19*
* Denotes values too low to be part of a viable brokerage contract with typical brokerage prices being in the range of $20 to $25 per ton of manure.

The most important observations that can be made from the results given in Table 4 are given below.

  • The value of broiler and turkey grow-out litter followed similar fluctuations. The values ranged from about $35 to $39 per ton in 2004 to a maximums of $94 to $107 per ton in 2008. By the end of 2016 the value of turkey grow-out litter and broiler litter ranged from about $40 to $47 per ton. During the years with high fertilizer prices brokerage customers that were paying $40 to $50 to spread 2 tons of litter per acre were receiving much more fertilizer value than they were paying for.
  • Turkey brooder litter consistently had the lowest value per ton as compared to the others due to low nutrient content and the large amounts of bedding used. The value of a ton of this type of litter was too low in 2004 and 2016 to be viable for litter brokerage contracts. Even during years with high fertilizer prices (2008 and 2012) turkey brooder litter was rarely brokered since it was so dry. Such dry, low-density manure that was mostly pine shavings further reduced the amount of litter and fertilizer value that could be fit into a typical trailer.
  • Layer manure consistently had lower value per ton as compared to broiler and turkey grow-out litter. The lower value was due to the much higher moisture content which diluted the nutrient value of the manure. Layer litter was a viable brokerage option, but not for long haul distances.

Value of Poultry Manure Applied to Fields with Sufficient P2O5

A common situation is when soil-test results indicate that a field has sufficient P2O5 in the soil for not only the crop to be grown immediately, but also for the next crop in the rotation (soybeans for example). In such cases, the P2O5 in poultry manure has no value, and only the N and K2O in the manure can be used as a fertilizer substitute. The results for this situation are provided in Table 5.

Table 5. Variation in the value of various types of poultry manure ($/ton) based on N and K2O prices. It was assumed that soil-test indicate that no P2O5 was needed.
Year Broiler (MC = 24%) Layer (MC = 47%) Turkey Grow-out (MC = 26%) Turkey Brooder (MC = 14%)
2004 19.95* 10.80* 16.05* 10.50*
2008 49.59 26.02 38.39 24.40
2010 43.13 22.45* 33.06 20.85*
2012 53.58 27.84 40.98 25.80
2016 29.45 15.53* 22.94* 14.65*
* denotes values are two low to be part of a viable brokerage contract with typical brokerage prices being in the range of $20 to $25 per ton of manure.

The results indicated that when the N price was $0.30/lb and K2O averaged $0.15/lb in 2004 the value of poultry manure was too low to be moved at contact prices of $20 to $25 per ton. Also, at prices associated with 2008, 2010, and 2012 the value of broiler and turkey grow-out litter ranged from $33 to $54 per ton. Layer and turkey brooder litter were poor to marginal values for brokerage contacts when the P2O5 was not needed over the entire range of fertilizer prices.

Comparing the results for 2008 for broiler litter indicates that if P2O5 was not needed the value fell from $107.01/ton to $49.59/ton. That is, the value of the litter was reduced by 54%. The year with the next highest value, 2012, eliminating the need for P2O5 reduced the litter value by 47%. Large drops in litter value can also be observed for other types of poultry manure by comparing the values in Tables 4 and 5. These results indicate that the P2O5 contained in poultry manure is one of the largest sources of value.

Value of Poultry Manure as Only a Source of Nitrogen

The analysis was performed again to reflect the value of poultry manure if nitrogen is the only major nutrient needed based on soil-test results. The results given in Table 6 clearly show that nitrogen alone never provided enough value to support brokerage contracts.

Table 6. Variation in the value of various types of poultry manure ($/ton) when nitrogen is the only nutrient needed based on soil-test results.
Year Broiler (MC = 24%) Layer (MC = 47%) Turkey Grow-out (MC = 26%) Turkey Brooder (MC = 14%)
2004 11.40* 6.90* 10.50* 7.50*
2008 22.80* 13.80* 21.00* 15.00*
2010 18.62* 11.27* 17.15* 12.25*
2012 22.80* 13.80* 21.00* 15.00*
2016 14.06* 8.51* 12.95* 9.25*
* denotes values are two low to be part of a viable brokerage contract with typical brokerage prices being in the range of $20 to $25 per ton of manure.

Results for a Four-House Broiler Farm

The previous results demonstrated that high litter nutrient contents combined with strong fertilizer prices yielded litter values that were much greater than the amount paid to litter brokers. The results also demonstrated that P2O5 was one of the key contributors to litter value.  The results of the analysis were applied to a four-house broiler farm to more clearly demonstrate the practical implications. Fertilizer prices from January 2019 in central South Carolina were also added to the analysis. The key assumptions and results are provided in Table 7.

Table 7. Application of analysis results to a 4-house broiler farm. Building size = 50 ft x 500 ft, litter production was assumed to be 580 tons/year (145 tons/house/yr) with a price of $10/ton paid to the broiler producer ($5800/year).
Year N Price ($/lb) P2O5 Price ($/lb) K2O Price ($/lb) Litter Value ($/ton) Value of 580 tons of litter ($/Year) Value from N (%) Value from P2O5 (%) Value From K2O (%) Loss to Producer ($/Year)
2004 0.30 0.29 0.15 39.09 22,672 29 49 22 16,872*
2008 0.60 0.87 0.47 107.01 62,066 21 54 25 56,266
2010 0.49 0.55 0.43 79.43 46,069 23 46 31 40,269
2012 0.60 0.72 0.54 101.1 58,638 23 47 30 52,838
2016 0.37 0.26 0.27 46.61 27,034 30 37 33 21,234
2019** 0.38 0.54 0.31 67.75 39,295 21 53 26 33,495
* The price paid to a broiler producer in a brokerage contract ranges from 0 to $15/ton of litter. A value of $10 /ton of litter is common. The loss was calculated as:  (litter value ($/ton) – $5800).
** Prices from central South Carolina obtained in January 2019.

The results indicate that the total value of litter on a four house farms that produces 580 tons of litter per year varied from $22,672 per year in 2004 to a maximum of $62,066 per year in 2008. Currently, the value in January 2019 was estimated to be $39,295/year.  In every year, the P2O5 contained in the litter contributed the most to the litter value. This contrasts with the common assumption that the high P2O5 content in litter is a problem as compared to nitrogen. The results point out that the most value can be obtained from litter by giving phosphorous use the priority in manure management. Assuming that the broiler producer was consistently paid $10/ton of litter by the broker the annual litter income was only $5800 per year. If the producer had integrated broiler production with crop production using a rotation that would realize all the fertilizer value in the litter the total litter value would have served to improve profitability of the cropping enterprise. If the producer relied on brokerage as the sole manure management strategy then the annual loss to the producer ranged from $16,872 to $56,266 per year depending on fertilizer prices.

What these results also point to, but do not quantify, is the variation in risk. Producers who built farms using brokerage as the sole manure management plan during the years of high fertilizer prices gave away litter that was worth 3.9 to 10.7 times more than they were paid. They also have incurred a great risk since brokerage contracts typically last only one year, and crop producers who once were happy to purchase brokered litter are no longer consistent customers.  Such producers are forced to quickly find other litter use alternatives often in areas where agricultural and forest land may not be close to the farm. Building broiler barns relying on annual brokerage contracts as the sole manure management option has been shown to be short sighted, and has a low probability of being economically or environmentally sustainable. Co-locating poultry production with some sort of profitable plant production enterprise that can use all of the fertilizer value in the litter is preferred. The next most viable alternative may be to use litter to produce high-quality compost for high volume, consistent markets.

What have we learned?

It was found that the value of poultry manure as a complete fertilizer (N,P,K) varied from $18.91 to $107.01 per ton depending of component prices (N, P, K), moisture content, and the amount of bedding used. If the receiving fields did not require phosphorous, based on soil test, the realized value ranged from $10.50 to $49.59 per ton. Finally, if soil-test indicate that N was the only major nutrient needed the value decreased to $7.50 to $22.80 per ton. During the same time frame, brokerage prices ranged from $20 to $50 per ton depending on haul distance and spreading service. However, most brokerage contracts were based on $20 to $25 per ton of manure.  Several practical observations were made from the results:

  1. Brokerage of litter may only be a viable alternative when the receiving cropland needs a complete fertilizer and when the N, P, and K contents of the manure are not diluted by water or bedding.
  2. Manure brokerage is not economically sustainable if N is the only major nutrient needed by the receiving cropland.
  3. Integrated farms that can use the manure produced by the poultry barns to fertilize their own cropland have the potential to reduce the legal and economic risk to the execution of a manure nutrient management plan.
  4. Poultry farms that currently rely on litter brokerage as the only manure management plan are losing customers and need to look at other alternatives that provide a less risky and sustainable use for the mature produced.
  5. Analysis of the impact of fluctuations in fertilizer price on litter produced from four broiler houses indicated that the full value of the litter ranged from $22,672 to $62,066 per year. The P2O5 contained in the litter accounted for the majority of the fertilizer value (37% to 54%). As a result, complete utilization of litter phosphorous in a crop rotation is the key to realizing the maximum value from litter.


John P. Chastain, Ph.D., Professor and Extension Agricultural Engineer
Department of Agricultural Sciences, Agricultural Mechanization & Business Program, Clemson University, 245 McAdams Hall, Clemson, SC 29634-0312 

Sources of Additional Information

Chastain, J.P., J.J. Camberato, and P. Skewes. (2001). Poultry Manure Production and Nutrient Content. Chapter 3B in Confined Animal Manure Managers Certification Program Manual: Poultry Version, Clemson University Extension, Clemson SC, pp 3b-1 to 3b-17. Available at:

DTN (2016). Fertilizer Trends: Prices Remain Steady, Mostly Lower from Oct. Available at:

USDA-ERS (2103), Fertilizer Use and Price. Available at:

USDA-SC (2016). Dept of Ag Market News, South Carolina Crop Production Report Dec. 8.

Zublena, J.P., J.V. Baird, and J.P. Lilly. (1997). SoilFacts: Nutrient Content of Fertilizer and Organic Materials (AG-439-18).


This study was supported by the Clemson Extension Confined Animal Manure Managers Program.



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. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.

Development and Application of the Newtrient Evaluation Assessment Tool (NEAT):  A Methodology for Comparing Manure Treatment Technologies

The recent development of the Newtrient on-line catalog (; see accompanying conference proceedings about the catalog) revealed the need to establish a set of environmental and farm operational based critical indicators (CIs).  The indicators are useful in identifying manure treatment technologies that primarily best address dairy farm environmental sustainability but include some social aspects.

What did we do?

The Newtrient Technical Advancement Team, comprised of academic and industry professionals in dairy manure management, developed and implemented a novel methodology that identifies technologies that best address dairy farm sustainability mainly from an environmental but also from a social perspective.  A project-amended process used by the International Organization for Standardization (ISO) was used as the basis for methodology development; the methodology is known as the Newtrient Evaluation and Assessment of Technology (NEAT) process.

For this work, six specific CIs were selected based on key environmental challenges/opportunities facing the dairy industry; they are:  nitrogen recovery, phosphorus recovery, liquid manure storage requirements, greenhouse gas reduction, odor reduction, and pathogen reduction.  A literature search was performed to evaluate 20 manure treatment technology types under five technology categories (Table 1).

A scoring system relative to the baseline condition of long-term (anaerobic) manure storage was developed and applied to each technology type and an appropriate relative score for each CI was determined.  The NEAT results are presented in an easy to understand dashboard called the NEAT Matrix (Figure 1).

What have we learned?

Use of the NEAT process across the 20 manure treatment technology types confirms that there is no single technology type that can address all the environmental and operational indicators.  An integrated manure management system that is comprised of strategically selected technologies may be assembled to move each dairy farm toward sustainability.

Table 1.  Technology categories and associated manure treatment technology types evaluated using the Newtrient Evaluation and Assessment of Technology (NEAT).
Technology Category Evaluated Technology Types
Primary solid-liquid separation
  • Centrifuge
  • Rotary screen
  • Screw press
  • Slope screen
Secondary solid-liquid separation
  • Clean water membrane
  • Evaporative technologies
  • Ultrafiltration membrane
Physical and biochemical stabilization
  • Active solids drying
  • Composting
  • Drum composter bedding
  • Surface aeration
Nutrient recovery
  • Ammonia stripping
  • Chemical flocculation
  • Struvite crystallization
  • Nitrification/denitrification
Energy recovery
  • Anaerobic digestion
  • Gasification
  • Hydrothermal Carbonization
  • Pyrolysis
  • Torrefaction
Figure 1. Generic example of the Newtrient Evaluation and Assessment of Technology (NEAT) Matrix
Figure 1. Generic example of the Newtrient Evaluation and Assessment of Technology (NEAT) Matrix

Future Plans

Future research in this area will continue to focus on using NEAT to evaluate integrated manure management systems designed specifically to achieve farm goals/needs.

Corresponding author, title, and affiliation

Curt Gooch, Environmental Systems Engineer, PRO-DAIRY Dairy Environmental System Program, Dept. of Animal Science, Cornell University.

Other authors

Mark Stoermann (Newtrient, LLC), Garth Boyd (Context), Dana Kirk (Michigan State University), Craig Frear (Regenis), and Frank Mitloehner (UC Davis).

Additional information

Additional project information, is available on the Newtrient website:


Newtrient, LCC and the paper authors thank the following supporters of Newtrient:  Agri-Mark, Inc., Dairy Farmers of America, Inc., Dairy Management Inc., Foremost Farms USA, Land O’Lakes, Inc., Maryland Virginia Milk Producers Cooperative Association, Inc., Michigan Milk Producers, National Milk Producers Federation, Prairie Farms Dairy, Inc., Select Milk Producers, Inc., Southeast Milk, Inc., St. Albans Cooperative Creamery, Tillamook County Creamery Association, and United Dairymen of Arizona


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. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.

Considerations in Evaluating Manure Treatment Systems for Dairy Farms

Advanced manure treatment may become a major system on some dairy farms in the future.  Reducing the impacts of excess nitrogen and or phosphorous may be necessary on farms with a limited or remote land base.  Additional treatments to recover solids, extract energy, concentrate nutrients, reduce odors, reduce the mass/volume, and/or reduce pathogens may become more of a priority as farms seek to move toward sustainability.  Potential systems should be evaluated from many perspectives including on an economic and effectiveness basis. There are many variables to consider in evaluating a manure management system. Potential systems should be selected based on many criteria including:  operational history, operational reliability, market penetration, capital cost, O&M cost, value proposition, and vendor information and documentation including case studies and customer reviews.

What did we do?

Manure management formally started in the second half of the 20th century with the development and implementation of the water quality best management practice (BMP) of long-term manure storage.  Storage provides farms with the opportunity to recycle manure to cropland when applied nutrients can be more efficiently used by the crop.  Many long-term manure storages were built to improve nutrient recycling and minimize risk. In some cases, anaerobic lagoons were built to both reduce the organic matter spread to fields and store manure.  Simultaneously as poultry and livestock consolidation escalated, more manure storages were built and their volume increased to reflect the recognized need to store manure longer. Cooperative Extension, Soil and Water Conservation Districts and Natural Resources Conservation Service have assisted in providing planning, design, construction and maintenance of these manure storage systems.

What have we learned?

Many lessons have been learned from storing manure long-term.  They include, but are not limited to:

    • While storing manure long-term reduces water quality impairment, it also produces and emits methane, a greenhouse gas.  Greenhouse gases are reported to contribute to global warming. The US dairy industry is under attack by some because of this, and it is likely that the decline in fluid milk sales has, in some part, been affected by this.  The lesson learned here is that the implementation of BMPs can have unintended consequences; therefore, all future BMPs need to be thoroughly vetted before substantial industry uptake happens in order to avoid undesirable unintended consequences.
    • Larger long-term storages are better than short-term (smaller) ones.  Storages that store manure for a longer period of time provide farms with increased flexibility when it comes to recycling manure to cropland.
    • Long-term storages can emit odors that can be offensive to neighbors and communities.  Farms have adopted improved manure spreading practices, namely direct incorporation, to reduce odor issues but incorporation doesn’t work well on some crops.  Some farms have also adopted anaerobic digestion as a long-term storage pre-treatment step in order to reduce odor emissions from storage and land application.
    • Substantial precipitation can accumulate in long-term storages located on farms in humid climates.  Increased storage surface area (generally an outcome of building larger storages) results in more precipitation to store and handle as part of the manure slurry.  Every acre-foot of net perception results in 325,900 gallons of additional slurry to store and spread. If each manure spreader load is 5,000 gallons, then this means 65 additional loads are required.
    • Neighbors of larger farms are more sensitive to intensive truck traffic than regular but low-level truck traffic.  Long-term storages require intensive, focused effort to empty and the over the road truck traffic can be offensive in some farm locations.
    • Insufficient storage duration results in the need to recycle manure to cropland during inopportune times and thus may not be contributing to the BMP goal.  Fall spreading is still required on many farms; however, it also may be unlikely that a sufficient spring planting window exists for farms to spread all their manure in the spring, avoid compacting wet soils and also get spring crops planted in time.
    • Where longer term storage duration and or incorporation of the manure to prevent odor emissions is needed to facilitate spring and summer manure spreading, farms may have more manure nutrients than needed to meet crop demand.

Future Plans

The above lessons learned support the need for advanced manure treatment systems on some farms that can also be used as the basis for considerations that should be included when evaluating all manure treatment systems.  It is important that the manure treatment equipment/system components and the overall system address the farm need(s) as best as possible. A challenge with evaluating the existing manure treatment equipment available to the farmer is the lack of performance and economic data.  Comparatively, advanced manure treatment (we define this as treatment above basic primary solid-liquid separation) is in its infancy stage of adoption and thus little field performance data exists. Our plans are to continue (as funding allows) to perform more on-farm manure treatment system evaluations and to report facts to our US dairy industry stakeholders.

Corresponding author, title, and affiliation

Curt Gooch, Environmental Systems Engineer, PRO-DAIRY Dairy Environmental System Program, Dept. of Animal Science, Cornell University

Other authors

Peter Wright, Agricultural Engineer, PRO-DAIRY Dairy Environmental System Program, Dept. of Animal Science, Cornell University

Additional information

Additional project information, including reports about on-farm assessment of manure treatment systems, is available on the Dairy Environmental System Program webpage:


New York State Department of Agriculture and Markets for their continued financial support of the PRO-DAIRY Program, the New York State Energy Research and Development Authority (NYSERDA) for funding many on-farm sponsored projects, and the US dairy farmers who have collaborated with us for over three decades.

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. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.

NRCS Solid-Liquid Separation Document – It is Finally Here!!

NRCS has a new technical document entitled “Solid-Liquid Separation Alternatives for Manure Handling and Treatment.”  It was created through efforts from Dr. John Chastain, Clemson University with funding provided by USDA-NRCS.

Screw press solid-liquid separator
Screw press solid-liquid separator (Source: USDA-NRCS)

This document brings together both the theory behind solid-liquid separation and the practical application of many different separation technologies.  Several farm scale demonstration projects are also summarized in the report. Solid-liquid separation can serve to achieve many livestock operational objectives such as nutrient partitioning, improved pumping characteristics, solids removal from storage facilities and reduced organic loadings.  The use of separation technologies is essential for many operations and has become an integral part of the efficient performance of these livestock facilities. Some of the purposes and uses of this document include assisting in solid-liquid separation technology selection, evaluating separation performance, and quantifying the impact of solid-liquid separation on manure management.  This presentation provides an overview of this document including methods of solid-liquid separation, influence of manure characteristics and handling methods, fundamentals of solid-liquid separation, performance of various solid-liquid separation technologies, unique separation technologies and applications and design considerations.

What Did We Do?

Use of coagulant and flocculant to enhance solid-liquid separation
Use of coagulant and flocculant to enhance solid-liquid separation (Source: USDA-NRCS)

Extensive effort through literature searches and testing went into compiling performance and design information on various types of solid-liquid separation technologies.  Separation theory was incorporated into the document to provide an understanding of separation principles and background information to assist in technology selection for improved system performance.  To improve usability of the document, it was divided into the following chapters: Methods of Solid-Liquid Separation, Manure Characteristics and Handling Methods, Fundamentals of Solid-Liquid Separation, Measures of Solid-Liquid Separation Performance, High-Rate Solid-Liquid Separation, Unique Applications of Solid-Liquid Separation Technology, and Design Considerations.  Several examples were provided throughout to assist in the design process of the various technologies. The document also includes information on the uses and benefits of coagulants and flocculants and separation methods associated with sand laden manure. Numerous system diagrams assist in illustrating the vast array of solid-liquid separation technologies that can be implemented in an animal manure treatment system.

What Have We Learned?

Sand settling land
Sand settling land (Source: USDA-NRCS)

This work brings together fundamental information about solid-liquid separation, benefits and limitations of many separation technologies, performance measurement techniques along with design considerations into one document.  Even though there are significant differences in performance and costs between the various separation technologies, the approach selected is largely dependent on critical elements such as landowner objectives, facility size, performance goals, operation and maintenance and other factors.  This document will help designers and operators choose the separation technology or technologies that will best meet the goals established for the operation.

Future Plans

This document will be published as chapter 4 of the USDA-NRCS National Engineering Handbook, Part 637 Environmental Engineering.


Jeffrey P. Porter, P.E.

Animal Manure and Nutrient Management Team Leader

USDA-Natural Resources Conservation Service

Additional information

Once published, a copy of the document can be found at


A special thank you goes out to the Piedmont-South Atlantic Coast Cooperative Ecosystems Studies Unit (CESU).  This Cooperative and Joint Venture Agreement allowed for this work to be completed.

Additional support was provided by the Confined Animal Manure Managers Program, Clemson Extension, Clemson University, Clemson, SC.

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. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.

Revenue Streams from Poultry Manure in Anaerobic Digestion (AD)

DUCTOR Corp. has developed a biological process that separates and captures nitrogen (ammonia) from organic waste streams. The biogas industry is a natural platform for this biotechnology as it solves the problem of ammonia inhibition, which has long bedeviled traditional anaerobic digestion (AD) processes. DUCTOR’s technology allows for stabilized and optimized biogas production from 100% high nitrogen feedstocks (such as poultry manure) and significantly strengthens the economics of biogas facilities: relatively inexpensive inputs, optimized gas production as well as new, higher value revenue streams from the organically produced byproducts—a pure Nitrogen fertilizer and a high Phosphorus soil amendment. DUCTOR’s mission is to promote biogas as a renewable energy source while securing efficient waste management and sustainable food & energy production, supporting the development of circular economies.


Figure 1. High Nitrogen Feedstock-molecular structure
Figure 1. High Nitrogen Feedstock

High concentrations of ammonia in organic waste streams have been a perpetual challenge to the biogas industry as ammonia is a powerful inhibitor of biogas production. In typical methanogenic communities, as ammonia levels exceed 1500mg/L Ammonia-N, the inhibition of methane production begins until it reaches toxic levels above 3000mg/L. Traditionally, various mechanical and chemical methods have been deployed to lower ammonia concentrations in high nitrogen organic feedstocks prior to or following biodigestion (Figure 1). These methods have proven cumbersome and operationally unstable. They either require dilution with often costly supplemental feedstocks, are fresh water intensive, waste valuable nutrients, or require caustic chemicals injurious to the environment. Without the application of these methods, nitrogen levels will build up in the digester and negatively affect the efficiency of biogas (methane) production. DUCTOR’s proprietary process revolutionizes ammonia removal with a biological approach, which not only optimizes the operational and economic performance of biogas production, it also allows for the ammonia to be recaptured and recycled as an organic fertilizer product (a 5-0-0 Ammonia Water). This biotechnical innovation represents a significant advancement in biogas technology.  

What did we do?

DUCTOR’s innovation is the invention of a fermentation step prior to the classic anaerobic digestion process of a biogas facility (Figure 2).  During this fermentation step in a pre-treatment tank, excess nitrogen is biologically converted into ammonia/ammonium and captured through a physical process involving volatilization and condensation of the liquid portion of the digestate.


Typical DUCTOR facility layout
Figure 2. Typical DUCTOR facility layout

We ran a demonstration biogas facility with these two steps in Tuorla, Finland for 2000 hours using 100% poultry litter as fermenter feedstock without experiencing ammonia inhibition of the methanogenesis process. While the control, a single-stage traditional digester, showed increased buildup of toxic ammonia, the fermented material coming out of the first stage of the DUCTOR process (having ~50-60% of its nitrogen volatilized and removed) exhibited uniform levels of nitrogen below the inhibition threshold (Figure 3). This allowed a stable and efficient digestion by the methanogenic microbial community in the second stage digester. The fermentation step effectively eliminates the need for co-digestion of poultry manures with other higher C/N ratio substrates.

Figure 3: Ammonium concentration & Methane quantities in treated and untreated substrates
Figure 3: Ammonium concentration & Methane quantities in treated and untreated substrates

What we have learned?

In addition to solving the problem of ammonia inhibition, DUCTOR’s innovation realizes the separation of valuable recycled nutrients in a manner that can produce additional revenue streams. The result of the fermentation process in the first stage digestion tank is an organically produced non-synthetic ammonia (NH4OH), which is condensed and collected. This ammonia water product can be marketed and sold as an organic fertilizer as it is the result of a completely biological process with no controlled chemical reactions. The non-synthetic ammonia produced comes from the digestion of poultry litter by ammonifying microorganisms in anaerobic conditions. Furthermore, this ammonia water is in a plant available form that can be metered onto fields based on crop demands and thus reduce the amount of excess nitrates leaching into the water table and surrounding watershed.

The solids byproduct that results from the completion of the anaerobic digestion process has a large fraction of phosphorus and potash. This digestate can be dried and pelleted to produce a high-phosphorus soil amendment. While recognizing demand for this product would vary by region based on existing phosphorus levels in the soil, it offers a transportable & storable way to return these valuable elements to the nutrient cycle.

nutrient life cycle

Finally, the importance of gas production as a form of sustainable, renewable energy cannot be understated. With 2/3rds of the world’s greenhouse gas emissions coming from the burning of fossil fuels for energy or electricity generation,1 biogas derived from anaerobic digestion can displace some of those processes and reduce environmental greenhouse gas emissions.2 Currently, there are many state and federal policies focusing on renewable energy credits and low carbon fuel standards to incentivize this displacement.3 With the ability to unlock poultry litter as an additional AD feedstock, biogas facilities can offer greater volumes of biogas production per ton of manure than either dairy or swine.

Future plans

We have several commercial projects that will feature the DUCTOR technology at various stages of development in North America. The demonstration facility at Tuorla has been disassembled and shipped to Mexico where it will be reassembled as part of a larger commercial project there. In cooperation with our Mexican partner, we will demonstrate successful operations under a new set of conditions, including different climate and a new source of poultry litter from different regional growing practices. We further intend to demonstrate the highly efficient water use of the process in a drought-prone area.

Additionally, we have received approval from the North Carolina Utilities Commission for entry into their pilot program for injecting biomethane into North Carolina’s natural gas pipelines. Our first project there is expected to begin construction in Spring 2019 to be completed and operational by early 2020. These projects, and others in development, will bring a very attractive and new manure management option to poultry farmers, while recycling nutrients from the waste stream and returning them to the soil in a measurable and sustainable manner.


Bill Parmentier, Project Development, DUCTOR Americas

Additional information


1Global Greenhouse Gas Emissions Data, US Environmental Protection Agency (EPA),

2Sources of Greenhouse Gas Emissions, US Environmental Protection Agency,

3Methane is a potent greenhouse gas that is over 20 times more damaging on the environment than carbon dioxide. Anaerobic digestion stops the release of methane into the environment by capturing it and using it for energy production or transportation fuel.

Federal incentives include the Rural Energy for America Program (REAP), Alternative Fuel Excise Tax Credit, & Federal Renewable Energy Production Tax Credit to name a few. Examples of state level incentives include various states Renewable Portfolio Standards (RPS) as well as California’s Low Carbon Fuel Standard (LCFS) or Oregon’s Clean Fuels Standard (CFS).


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. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.

Minnesota’s Runoff Risk Advisory Forecast: Forecasting the optimal time for manure application

The Runoff Risk project was started in Wisconsin in 2011, with the realization at that time, there was no real-time runoff risk guidance available for manure applicators. The project has grown, with four states (Michigan, Minnesota, Ohio and Wisconsin) now operating real-time runoff risk forecast websites.

screenshot of Minnesota runoff risk advisory forecast
Figure 1. Minnesota Runoff Risk Advisory Forecast from July 1, 2018.

The Minnesota Runoff Risk Advisory Forecast (RRAF) system is a tool developed by the Minnesota Department of Agriculture (MDA) and the National Weather Service (NWS). It is designed to help farmers and commercial applicators determine the best time to apply manure to reduce the runoff risk of valuable nutrients and protect water resources. It is part of a regional risk advisory forecast project that utilizes existing NWS weather and watershed models in a water quality application. Figure 1 shows a screenshot of the website from July 1, 2018, indicating the runoff risk forecast in the central part of the state.

Runoff Risk Analysis

The NWS models continuously simulate soil moisture and temperature conditions as well as incorporating future precipitation and temperature forecasts and current and future snowpack. An algorithm that looks at chosen model state values is evaluated for a variety of risk conditions, such as runoff and soil saturation. Based on over 20 years of simulations, basin specific thresholds were created. Finally, there was post–processing of that data that is run on the output to produce risk events. This information is provided daily to the project partners through data servers. The data is processed and the website is updated twice daily. The graphic displays the different risk events predicting the likelihood of today (Day 1), tomorrow (Day 2), and Day 3 or multi-day (Day 1 through Day 3 combined) runoff events. Farmers and commercial applicators use an interactive map to locate their field and find their forecasted risk. Users can also sign up for email or text messages for their county that alert them to a severe runoff risk for that day.

screenshot of tabular format risk advisory forecast
Figure 2. Tabular 5 day forecast from June 24, 2019 in Bandon Township, Renville County, Minnesota.

Runoff risk is grouped into four categories: No event, Low, Moderate and Severe. When the risk is Moderate or Severe, it is recommended that the applicator evaluate the situation to determine if there are other locations or later dates when the application could take place. Figure 2 shows results for a specific location in Bandon Township in Renville County, Minnesota. For the first three days, the risk of runoff at that specific location was Severe, which indicated that a producer should wait to apply.

Daily Mapping Information

screenshot of soil temperature map
Figure 3. Daily soil temperature forecast at 6 inch depth for Minnesota.

The RRAF website also provides statewide forecasted daily average two inch soil depth temperatures which can be useful at planting time, daily average six inch soil depth temperatures which are helpful when determining fall fertilizer application in appropriate areas and daily precipitation forecasts. Figure 3 shows the daily soil temperature forecast at the six inch depth for the state of Minnesota. The colored dots are real time soil temperature gauges that can be interactively clicked on to reveal current soil temperature. The color of the dot is not reflective of the temperature at the gauge. It simply notes what entity is in charge of the gauge.

Potential of RRAF

This is a relatively new application that has been implemented in Minnesota since March 2018. The potential impacts of usage on this could be quite large. Any time movement of manure to water resources can be minimized is a success for the farmer and the environment. The overall goal of the presentation is to make people aware of this tool, share information on the performance, and encourage potential users to add this tool to their “toolbox”. The main message is to check conditions, delay if necessary, and spread on the day when there is least potential impact to the environment.

Further partnerships are desired to continue to get the word out on this application. Yearly multi-state coordination meetings occur, with the next meeting coming up in Ohio in August 2019. Version 3 of the RRAF will be derived from the National Weather Service National Water Model. Development on this version will start in Spring 2019 and should take four years for it to be merged into the National Water Model system. For MDA, we continue to promote RRAF website and monitor the output, comparing it to real time data to make sure that the model is working correctly.

Heather Johnson, Hydrologist 3, Minnesota Department of Agriculture

Additional information



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. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.

Regional Runoff Risk Tools for Nutrient Reduction in Great Lakes States

One method to reduce the impacts of excess nutrients leaving agricultural fields and degrading water quality across the Nation is to ensure nutrients are not applied right before a runoff event could occur.  Generally nutrient management approaches, including the 4-Rs (“right” timing, rate, placement, and source), include some discussion about the “right time” for nutrient applications, however that information is static guidance usually centered on the timing of crop needs.  What has been missing, and what will be discussed in this talk, will be the development and introduction to runoff risk decision support tools focused on providing farmers and producers real-time guidance on when to not apply nutrients in the next week to 10 days due to the risk of runoff capable of transporting those nutrients off their fields.  The voluntary adoption and use of runoff risk in short-term field management decisions could provide both environmental and economic benefits.

In response to the need for real-time nutrient application guidance and a request from states in the Great Lakes region, the National Weather Service (NWS) North Central River Forecast Center (NCRFC) has helped develop these runoff risk tools in collaboration with multiple state agencies and universities and with support from the Great Lakes Restoration Initiative (GLRI).  There are currently four active runoff risk tools in the Great Lakes region: Michigan, Minnesota, Ohio, and Wisconsin.  It is possible to develop similar tools for Illinois, Indiana, and New York if willing state partners are identified.  

What did we do?

Studies have shown that a few large runoff events per year contribute a majority of the annual load leaving fields.  In addition applications generally occur during the riskiest times of year for runoff (fall through spring) when fields experience the least vegetative cover and soils are vulnerable.  Knowing this information, real-time NWS weather and hydrologic models were evaluated to identify conditions that correlated with runoff observed at edge-of-field (EOF) locations.  The runoff risk algorithm identifies daily runoff events and stratifies the events by magnitude respective to each grid cell’s historical behavior.  The events are then classified into risk categories for the farmers and producers. In general, high risk events are larger magnitude events that don’t happen as often and also have a higher accuracy rate.  On the other end, low risk events are smaller magnitude events that have a higher chance of being a false alarm yet are also less likely to be associated with significant nutrient loss.

NWS models are run twice daily and simulate soil temperature, soil moisture, runoff, and snowpack conditions continuously.  The runoff risk algorithm is applied against the model output to produce runoff risk guidance which is sent to the state partners.  Each state has a working group and a lead agency or organization that manages the effort to produce and maintain the runoff risk websites as well as promote the tools and educate the users on how to interpret and use the guidance.  

What have we learned?

At this point there are four regional runoff risk tools available.  Response has been positive from both state agencies and when farming groups are asked about the runoff risk concept during post-presentation surveys and small focus groups.  There is a strong desire from the farming community to make the best decision during stressful times of the year when farming schedules and the weather are often in conflict.  

At this point, it is universally accepted among the runoff risk collaborators that there is a need to provide free, easily obtainable forecast guidance to the farming community so they can make the best nutrient application decisions for their operations and the environment.

Runoff risk tools are strictly for decision support and not meant to be a regulatory tool in nature.  This is due to the limitations in hydrologic models, weather forecasting, spatial scale issues, and that the tools have no way of incorporating farmer specific practices into the risk calculations.  Although model improvements will occur in the future, ensuring users understand the limitations but also the benefits they can provide are important components in the States’ outreach and education functions.  

Future Plans

Based on feedback from the states employing runoff tools, there is a second round of enhancement planned for the runoff risk algorithm in the summer of 2019.  Other improvements from the states’ perspective deal with updating webpages and building on and enhancing push notification capabilities such as text message and email alerts.

The next major step forward begins in spring 2019 with the start of version 3 runoff risk.  This 2-year development will transition runoff risk guidance from the current model over to the new NWS National Water Model (NWM).  The NWM framework will allow finer resolution guidance (1km or smaller) for numerous models runs per day all with full operational support.  Moving to the NWM also allows continuous improvement and future collaboration opportunities with universities to improve the underlying WRF-Hydro model as well as runoff risk and other derived decision support guidance.


Dustin Goering, Senior Hydrologist, North Central River Forecast Center, National Weather Service
Andrea Thorstensen, Hydrologist, North Central River Forecast Center, National Weather Service

Corresponding Author email

Additional Information

For further information on runoff risk background please visit this page:  (Still under construction)


To visit the state tools see the following links:







There are many individuals across a wide spectrum of agencies, industry, and universities that have been instrumental in the development of runoff risk to this point.

Support for the development of runoff risk across the Great Lakes and the upcoming version 3 runoff risk from the National Water Model has been provided by multi-year grants from the Great Lakes Restoration Initiative.



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. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.

An Economical Method to Install Industrial Wastewater Storage Pond Liners

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Over the past four decades, the number of custom slaughterhouses in Michigan has steadily decreased as the number of livestock producers declined. Those who remain are growing larger as they capitalize on the buy local food craze by providing fresh USDA-approved boxed meats at a meat counter or by adding value to the meats by further processing (i.e., sausages, hams, etc.). All slaughterhouses in the State are regulated by the Michigan Department of Environmental Quality (MDEQ) who issues permits for the proper disposal of the process wastewater for those operations that are not connected to a municipal sewer.

Typical disposal of the process wastewater involves removal of the solids through septic tank filtration and screens followed by storage of the process wastewater in ponds for eventual disposal on crop ground at agronomic rates. Facilities operating in this manner are issued a Groundwater Discharge Permit from MDEQ. However, because the state classifies slaughterhouses as an industry, the storage ponds require double liners and must meet a hydraulic conductivity of 1 x 10-7 centimeters/second.

A process wastewater storage pond is being designed for a slaughterhouse located in Coopersville, Michigan. The existing process wastewater holding pond is not sufficient to hold process water generated at the facility due to the recent expansions in slaughterhouse operations. Therefore, modifications to the existing holding pond and construction of a new holding pond to accommodate the process water generated is underway. The construction of the ponds is scheduled for spring 2017.

This paper evaluates the applicability, economic feasibility compared to geomembrane liners and constructability of pond liners using AquaBlok.

AquaBlok is a man-made clay pellet material that handles like gravel and is placed in varying thicknesses depending on the desired hydraulic conductivity and then hydrated to create a low permeable liner. Advertised as a “composite particle system” each AquaBlok particle contains an individual piece of limestone as its core. When a continuous layer of individual particles is applied, the clay (i.e., a high-quality sodium bentonite coating) surrounding each stone hydrates, swells, and binds together to produce a low-permeable earthen liner when introduced to a water environment.

What did we do? 

Based on the current operations and future growth forecast, the slaughterhouse requires a pond(s) with total holding capacity of approximately 1.6 million gallons of process wastewater. This accounts for process wastewater generated in total of eight (8) months period. Soil borings were taken at the site and soil samples were collected to determine geotechnical parameters including hydraulic conductivity. Total of eight (8) soil borings were advanced to an approximate depth of fifty (50) feet below ground surface. Based on the laboratory testing results, the hydraulic conductivity of the native clay did not meet the MDEQ’s minimum 1 x 10-7 cm/s requirement. These results indicate a need for a composite liner for the existing pond as well as the new pond. Two candidate liner materials are being evaluated. They are 1) clay liner that is constructed of AquaBlok and 2) geomembrane liner. Geomembrane are commonly being used for wastewater! holding ponds. AquaBlok is not being frequently used as liners for holding ponds. However, once constructed appropriately, this material would provide a liner with hydraulic conductivity of less than 1 x 10-8 cm/s and appropriate shear and compressive strength. Currently, the economic feasibility of the two methods is being evaluated. Also, the constructability of the AqaBlok liners is being investigated. The ponds are scheduled to be constructed in Spring 2017.

What have we learned? 

The evaluation of AquaBlok as a liner material for process wastewater holding ponds is being evaluated. The construction of the ponds is scheduled for Spring 2017. This material has promising geotechnical parameters and can provide a liner with a very low permeability once constructed appropriately. A detailed discussion of the material evaluation, liner construction methodology, economic analysis, and regulatory compliance will be presented during the oral presentation.

Use of a geotextile liner is an approved method to construct industrial wastewater storage ponds in Michigan but cost and liner installer availability is typically a detriment to fast installations.

Future Plans    

Due to a plant expansion, the design drawings and application to expand the process wastewater pond capacity and to meet the state requirements for minimum liner permeability are currently in review by the state MDEQ. Construction of the new storage pond is planned for spring 2017 pending MDEQ review and approval.

Corresponding author, title, and affiliation        

Matthew J. Germane, PE, Senior Project Engineer at Environmental Resources Group, LLC

Corresponding author email

Other authors   

Mala Hettiarachchi, Ph.D, PE, Senior Engineer at Environmental Resources Group, LLC

Additional information                

Additional information on Michigan’s rules for liner construction of industrial wastewater is available at:


The authors wish to acknowledge DeVries Meats, Inc., in Coopersville, MI and their owner, Ken DeVries, whose site the design work and cost evaluations were completed for.

Poultry Mortality Freezer Units: Better BMP, Better Biosecurity, Better Bottom Line.

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Why Tackle Mortality Management?  It’s Ripe for Revolution.

The poultry industry has enjoyed a long run of technological and scientific advancements that have led to improvements in quality and efficiency.  To ensure its hard-won prosperity continues into the future, the industry has rightly shifted its focus to sustainability.  For example, much money and effort has been expended on developing better management methods and alternative uses/destinations for poultry litter.

In contrast, little effort or money has been expended to improve routine mortality management – arguably one of the most critical aspects of every poultry operation.  In many poultry producing areas of the country, mortality management methods have not changed in decades – not since the industry was forced to shift from the longstanding practice of pit burial.  Often that shift was to composting (with mixed results at best).  For several reasons – improved biosecurity being the most important/immediate – it’s time that the industry shift again.

The shift, however, doesn’t require reinventing the wheel, i.e., mortality management can be revolutionized without developing anything revolutionary.  In fact, the mortality management practice of the future owes its existence in part to a technology that was patented exactly 20 years ago by Tyson Foods – large freezer containers designed for storing routine/daily mortality on each individual farm until the containers are later emptied and the material is hauled off the farm for disposal.

Despite having been around for two decades, the practice of using on-farm freezer units has received almost no attention.  Little has been done to promote the practice or to study or improve on the original concept, which is a shame given the increasing focus on two of its biggest advantages – biosecurity and nutrient management.

Dusting off this old BMP for a closer look has been the focus of our work – and with promising results.  The benefits of hitting the reset button on this practice couldn’t be more clear:

  1. Greatly improved biosecurity for the individual grower when compared to traditional composting;
  2. Improved biosecurity for the entire industry as more individual farms switch from composting to freezing, reducing the likelihood of wider outbreaks;
  3. Reduced operational costs for the individual poultry farm as compared to more labor-intensive practices, such as composting;
  4. Greatly reduced environmental impact as compared to other BMPs that require land application as a second step, including composting, bio-digestion and incineration; and
  5. Improved quality of life for the grower, the grower’s family and the grower’s neighbors when compared to other BMPs, such as composting and incineration.

What Did We Do?

We basically took a fresh look at all aspects of this “old” BMP, and shared our findings with various audiences.

That work included:

  1. Direct testing with our own equipment on our own poultry farm regarding
    1. Farm visitation by animals and other disease vectors,
    2. Freezer unit capacity,
    3. Power consumption, and
    4. Operational/maintenance aspects;
  2. Field trials on two pilot project farms over two years regarding
    1. Freezer unit capacity
    2. Quality of life issues for growers and neighbors,
    3. Farm visitation by animals and other disease vectors,
    4. Operational and collection/hauling aspects;
  3. Performing literature reviews and interviews regarding
    1. Farm visitation by animals and other disease vectors
    2. Pathogen/disease transmission,
    3. Biosecurity measures
    4. Nutrient management comparisons
    5. Quality of life issues for growers and neighbors
  4. Ensuring the results of the above topics/tests were communicated to
    1. Growers
    2. Integrators
    3. Legislators
    4. Environmental groups
    5. Funding agencies (state and federal)
    6. Veterinary agencies (state and federal)

What Have We Learned?

The breadth of the work at times limited the depth of any one topic’s exploration, but here is an overview of our findings:

  1. Direct testing with our own equipment on our own poultry farm regarding
    1. Farm visitation by animals and other disease vectors
      1. Farm visitation by scavenger animals, including buzzards/vultures, raccoons, foxes and feral cats, that previously dined in the composting shed daily slowly decreased and then stopped entirely about three weeks after the farm converted to freezer units.
      2. The fly population was dramatically reduced after the farm converted from composting to freezer units.  [Reduction was estimated at 80%-90%.]
    2. Freezer unit capacity
      1. The test units were carefully filled on a daily basis to replicate the size and amount of deadstock generated over the course of a full farm’s grow-out cycle.
      2. The capacity tests were repeated over several flocks to ensure we had accurate numbers for creating a capacity calculator/matrix, which has since been adopted by the USDA’s Natural Resources Conservation Service to determine the correct number of units per farm based on flock size and finish bird weight (or number of grow-out days) in connection with the agency’s cost-share program.
    3. Power consumption
      1. Power consumption was recorded daily over several flocks and under several conditions, e.g., during all four seasons and under cover versus outside and unprotected from the elements.
      2. Energy costs were higher for uncovered units and obviously varied depending on the season, but the average cost to power one unit is only 90 cents a day.  The total cost of power for the average farm (all four units) is only $92 per flock.  (See additional information for supporting documentation and charts.)
    4. Operational/maintenance aspects;
      1. It was determined that the benefits of installing the units under cover (e.g., inside a small shed or retrofitted bin composter) with a winch system to assist with emptying the units greatly outweighed the additional infrastructure costs.
      2. This greatly reduced wear and tear on the freezer component of the system during emptying, eliminated clogging of the removable filter component, as well as provided enhanced access to the unit for periodic cleaning/maintenance by a refrigeration professional.
  2. Field trials on two pilot project farms over two years regarding
    1. Freezer unit capacity
      1. After tracking two years of full farm collection/hauling data, we were able to increase the per unit capacity number in the calculator/matrix from 1,500 lbs. to 1,800 lbs., thereby reducing the number of units required per farm to satisfy that farm’s capacity needs.
    2. Quality of life issues for growers and neighbors
      1. Both farms reported improved quality of life, largely thanks to the elimination or reduction of animals, insects and smells associated with composting.
    3. Farm visitation by animals and other disease vectors
      1. Both farms reported elimination or reduction of the scavenging animals and disease-carrying insects commonly associated with composting.
    4. Operational and collection/hauling aspects
      1. With the benefit of two years of actual use in the field, we entirely re-designed the sheds used for housing the freezer units.
      2. The biggest improvements were created by turning the units so they faced each other rather than all lined up side-by-side facing outward.  (See additional information for supporting documentation and diagrams.)  This change then meant that the grower went inside the shed (and out of the elements) to load the units.  This change also provided direct access to the fork pockets, allowing for quicker emptying and replacement with a forklift.
  3. Performing literature reviews and interviews regarding
    1. Farm visitation by animals and other disease vectors
      1. More research confirming the connection between farm visitation by scavenger animals and the use of composting was recently published by the USDA National Wildlife Research Center:
        1. “Certain wildlife species may become habituated to anthropogenically modified habitats, especially those associated with abundant food resources.  Such behavior, at least in the context of multiple farms, could facilitate the movement of IAV from farm to farm if a mammal were to become infected at one farm and then travel to a second location.  …  As such, the potential intrusion of select peridomestic mammals into poultry facilities should be accounted for in biosecurity plans.”
        2. Root, J. J. et al. When fur and feather occur together: interclass transmission of avian influenza A virus from mammals to birds through common resources. Sci. Rep. 5, 14354; doi:10.1038/ srep14354 (2015) at page 6 (internal citations omitted; emphasis added).
    2. Pathogen/disease transmission,
      1. Animals and insects have long been known to be carriers of dozens of pathogens harmful to poultry – and to people.  Recently, however, the USDA National Wildlife Research Center demonstrated conclusively that mammals are not only carriers – they also can transmit avian influenza virus to birds.
        1. The study’s conclusion is particularly troubling given the number and variety of mammals and other animals that routinely visit composting sheds as demonstrated by our research using a game camera.  These same animals also routinely visit nearby waterways and other poultry farms increasing the likelihood of cross-contamination, as explained in this the video titled Farm Freezer Biosecurity Benefits.
        2. “When wildlife and poultry interact and both can carry and spread a potentially damaging agricultural pathogen, it’s cause for concern,” said research wildlife biologist Dr. Jeff Root, one of several researchers from the National Wildlife Research Center, part of the USDA-APHIS Wildlife Services program, studying the role wild mammals may play in the spread of avian influenza viruses.
    3. Biosecurity measures
      1. Every day the grower collects routine mortality and stores it inside large freezer units. After the broiler flock is caught and processed, but before the next flock is started – i.e. when no live birds are present,  a customized truck and forklift empty the freezer units and hauls away the deadstock.  During this 10- to 20- day window between flocks biosecurity is relaxed and dozens of visitors (feed trucks, litter brokers, mortality collection) are on site in preparation for the next flock.
        1. “Access will change after a production cycle,” according to a biosecurity best practices document (enclosed) from Iowa State University. “Empty buildings are temporarily considered outside of the [protected area and even] the Line of Separation is temporarily removed because there are no birds in the barn.”
    4. Nutrient management comparisons
      1. Research provided by retired extension agent Bud Malone (enclosed) provided us with the opportunity to calculate nitrogen and phosphorous numbers for on-farm mortality, and therefore, the amount of those nutrients that can be diverted from land application through the use of freezer units instead of composting.
      2. The research (contained in an enclosed presentation) also provided a comparison of the cost-effectiveness of various nutrient management BMPs – and a finding that freezing and recycling is about 90% more efficient than the average of all other ag BMPs in reducing phosphorous.
    5. Quality of life issues for growers and neighbors
      1. Local and county governments in several states have been compiling a lot of research on the various approaches for ensuring farmers and their residential neighbors can coexist peacefully.
      2. Many of the complaints have focused on the unwanted scavenger animals, including buzzards/vultures, raccoons, foxes and feral cats, as well as the smells associated with composting.
      3. The concept of utilizing sealed freezer collection units to eliminate the smells and animals associated with composting is being considered by some government agencies as an alternative to instituting deeper and deeper setbacks from property lines, which make farming operations more difficult and costly.

Future Plans

We see more work on three fronts:

  • First, we’ll continue to do monitoring and testing locally so that we may add another year or two of data to the time frames utilized initially.
  • Second, we are actively working to develop new more profitable uses for the deadstock (alternatives to rendering) that could one day further reduce the cost of mortality management for the grower.
  • Lastly, as two of the biggest advantages of this practice – biosecurity and nutrient management – garner more attention nationwide, our hope would be to see more thorough university-level research into each of the otherwise disparate topics that we were forced to cobble together to develop a broad, initial understanding of this BMP.

Corresponding author (name, title, affiliation)

Victor Clark, Co-Founder & Vice President, Legal and Government Affairs, Farm Freezers LLC and Greener Solutions LLC

Corresponding author email address

Other Authors

Terry Baker, Co-Founder & President, Farm Freezers LLC and Greener Solutions LLC

Additional Information

Farm Freezer Biosecurity Benefits

One Night in a Composting Shed

Transmission Pathways

Avian flu conditions still evolving (editorial)

USDA NRCS Conservation fact sheet Poultry Freezers When fur and feather occur together: interclass transmission of avian influenza A virus from mammals to birds through common resources

How Does It Work? (on-farm freezing)

Influenza infections in wild raccoons (CDC)

Collection Shed Unit specifications

Collection Unit specifications

Freezing vs Composting for Biosecurity (Render magazine)

Manure and spent litter management: HPAI biosecurity (Iowa State University)


Bud Malone, retired University of Delaware Extension poultry specialist and owner of Malone Poultry Consulting

Bill Brown, University of Delaware Extension poultry specialist, poultry grower and Delmarva Poultry Industry board member

Delaware Department of Agriculture

Delaware Nutrient Management Commission

Delaware Office of the Natural Resources Conservation Service

Maryland Office of the Natural Resources Conservation Service

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. 2017. Title of presentation. Waste to Worth: Spreading Science and Solutions. Cary, NC. April 18-21, 2017. URL of this page. Accessed on: today’s date.