Tag: land application

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Ammonia Loss Following Application of Swine Manure

Purpose

The amount of nitrogen lost to the air as ammonia following the application of manure is important for two reasons. From the farmer’s point of view, the loss of nitrogen as ammonia gas represents a loss of fertilizer that could have contributed to the production of a crop. From an environmental point of view, ammonia lost from a field to the atmosphere is a source of air pollution that can combine with sulfites and nitrates in the atmosphere to form extremely fine particulate matter (PM2.5) that can have harmful effects on human health and can contribute to water pollution when deposited into surface water by rainfall. Land application of animal manure is one of many sources of ammonia emissions that also include municipal and industrial waste treatment, use and manufacture of fertilizers, combustion of fossil fuel, coke plants and refrigeration (USEPA, 1995).

Animal manure can be used as a fertilizer substitute. However, the types of nitrogen in manure are more complicated than those found in most common chemical fertilizers. Nitrogen can be present in manure as ammonium-N, ammonia-N, organic-N, and nitrate-N. Not all the nitrogen in manure is immediately available for plant use. Most animal manure contains very little nitrate-N and as a result it is typically not measured. However, manure that receives aerobic treatment, i.e., composting or aeration, should be analyzed for nitrate-N since it is a valuable form of nitrogen that is the same as contained in one of the most common types of fertilizer – ammonium nitrate.

Most laboratories measure the total ammoniacal nitrogen content (TAN) of animal manure, which includes ammonium-N and ammonia-N (TAN = NH4+-N + NH3 -N). The amount of TAN that is in the ammonia form depends greatly on the pH of the manure. At a pH of 6.5 none of the TAN is in the ammonia form – it is all ammonium-N which is a great form of plant fertilizer.  At a high pH, such as, 9.5, 65% of the TAN is in the ammonia form. Most animal manures have a pH in the range of 8 to 8.5 and about 10% most of the TAN is ammonia-N and can be lost to the air. As a result, TAN is often labeled as ammonium-N on manure analysis reports.

A key aspect of using animal manure as a fertilizer substitute is to make a good estimate of the fraction of the total nitrogen contained in the animal manure that can be used to grow a plant. This portion of the nitrogen is called the plant available nitrogen (PAN) and can be estimated using the following equation:

PAN =mf Organic-N + Af TAN + Nitrate-N. (1)

Most of the nitrogen in untreated slurry and solid animal manure is organic nitrogen (organic-N) that must be mineralized in the soil to become available to plants as ammonium-N. The fraction of the organic-N that will be mineralized during the growing season is represented in equation 1 as the mineralization factor, mf. The value of the mineralization factor varies depending on animal species, the amount of treatment, as well as soil pH, moisture, and temperature. The values of mf recommended are 0.70 for lagoon water and 0.50 for swine slurry (Chastain, 2006).

The fraction of TAN in manure that will be available to the plant is represented by the ammonium-N availability factor, Af. The ammonium-N availability factor (a decimal) is determined from the fraction of TAN lost to the air as ammonia-N using the following formula:

Af =1-( AL/ 100). (2)

The amount of ammonia-N lost following application varies with the method of application, the extent and timing of incorporation in the soil by disking as well as the pH of the manure, the pH that the manure attains following application, and the air temperature. Most extension publications provide recommended values for estimating ammonia-N losses. For example, Clemson Cooperative Extension (CAMM, 2005) recommends use of an ammonia loss (AL) of 50% for broadcast of manure without incorporation. This would mean that a value of 0.5 is used for ammonium-N availability factor (Af) in equation 1. If the manure is incorporated into the soil within one day the recommended value for AL is 20% giving an Af value of 0.80.

The amount of nitrate-N contained in animal manure is often so small that it is not measured. However, manure that is exposed to enough air or that is treated aerobically will have a significant amount and measurement of the nitrate-N content is recommended. All the nitrate-N contained in manure is 100% plant available.

Various studies and reviews (Chastain, et al., 2001; Montes, 2002; Montes and Chastain, 2003; Chastain, 2006) have indicated that the amount of ammonia lost following application of animal manure varies much more than indicated by most extension recommendations (e.g., CAMM, 2005). The result of large differences between recommended estimates and actual values is either substantial over or under estimation of the amount of ammonia emissions to the air as well as over or underestimation of the amount of nitrogen that will be available for the plant. The objective of this paper is to provide practical recommendations for the ammonium-N availability factors for swine manure based on the application method, total solids content, and the time between broadcast and incorporation.

What Did We Do?

The data and the correlations used to develop the recommendations in this paper were provided by Montes (2002) and Chastain (2006).  The effect of the application method on ammonia-N loss was estimated using the following equation:

AL =fA ALBC. (3)

The application factors, fA, that correspond to an application method are given in Table 1 and ALBC was the ammonia loss for broadcast manure. The value of the ammonium-N availability factor, Af, for each application method was calculated using the definition given previously in equation 2.

How fast ammonia is lost following broadcast application of manure was determined by Montes (2002). The results indicated that ammonia-N loss following irrigation of lagoon water occurred too quickly to consider incorporation by disking. Values for broadcast and incorporation for slurry manure are given in Table 1. The results indicated that incorporation must follow broadcast of slurry manure within 8 hours if it is desired to reduce ammonia-N loss by 50% (fA=0.50).

 

Table 1. Application method factors to describe the reduction in ammonia loss as compared to broadcast application of manure. (Values based on reviews of the literature by Chastain et al., 2001 and Montes, 2002).
Application Method fA What type of manure can use this method?
Broadcast without incorporation 1.0 All
Broadcast followed by incorporation within 4 hoursA 0.29 Slurry
Broadcast followed by incorporation within 6 hoursA 0.40 Slurry
Broadcast followed by incorporation within 8 hoursA 0.50 Slurry
Broadcast followed by incorporation within 12 hoursA 0.64 Slurry
Band spreading (drop or trailing hose) 0.50 Liquid and Slurry
Band spreading with immediate shallow soil cover 0.12 Liquid and Slurry
Shallow injection (2 to  inches below soil surface) 0.10 Liquid and Slurry
Deep injection (4 to 6 inches below soil surface) 0.08 Liquid and Slurry
AfA calculated using K = 0.086 h-1 (Chastain, 2006)

A few studies indicated that application of manure to bare soil versus cut hay, or plant residue reduced ammonia-N loss following broadcast by 10% to 20% (see Montes, 2002 and Chastain, 2006). However, it was decided that there was not sufficient data to generalize the result for practical use.

What Have We Learned?

The model was applied to as wide a range of swine manure application situations as possible. The results were tabulated as ammonium-N availability factors, Af, that may be used in the PAN equation (equation 1) along with an estimate for the mineralization factor.

Variation in Ammonium-N Availability by Application Method

The impact of application method on the ammonium-N availability factor for swine manure is shown in Table 2. Application method had the least impact on irrigation of surface water from an anaerobic treatment lagoon. The value of Af was 0.98 for irrigated swine lagoon water. This corresponded to an ammonia-N loss of 2% (AL = (1-Af) x 100). The amount of ammonia-N lost was low since more than 0.25 inches of lagoon water was applied, and most of the ammonium-N was washed into the soil. However, the ammonium-N availability factors for broadcast of manure decreased sharply as the total solids content of swine manure increased. This corresponded to ammonia-N loss ranging from 8% for liquid manure (TS = 1% to 4%) to 58% for thick slurry (TS = 15% to 20%). It can also be seen in the table that all the ammonium-N conserving application methods increased in effectiveness as the TS content of swine manure increased.

 

Table 2. Variation in ammonium nitrogen availability factors, Af, for swine manure and treatment lagoon surface water based on application method. (AL = (1 – Af) x 100)
Description Broadcast or Large Bore Irrigation Broadcast followed by incorporation within 6 hours Band Spreading Band Spreading with Shallow Cover Shallow Injection Deep Injection
Lagoon Surface WaterA 0.98 NA 0.99 1.00 1.00 1.00
Liquid or SlurryB
TS=1% to 4% 0.92 0.97 0.96 0.99 0.99 0.99
TS=5% to 6% 0.82 0.93 0.91 0.98 0.98 0.99
TS=7% to 8% 0.75 0.90 0.88 0.97 0.98 0.98
TS=9% to 12% 0.66 0.86 0.83 0.96 0.97 0.97
TS=13% to 14% 0.56 0.82 0.78 0.95 0.96 0.96
TS=15% to 20% 0.42 0.77 0.71 0.93 0.94 0.95
AALBC = 14.30 TS – 4.75, R2 = 0.791, TS = 0.5%, Chastain (2006)
BALBC = 23.284 TS, R2 = 0.875, Chastain (2006)

Comparison of the Use of New Ammonium-N Availability Factors and Current Clemson Extension Recommendations for Broadcast Application of Swine Manure

Selection of the ammonium-N availability factor (Af) and mineralization factor (mf) for a manure type and application method has a large effect on the accuracy of the estimate of nitrogen that can be used to fertilize a crop as well as the estimate of ammonia-N lost to the air. The PAN estimate determines the amount of manure applied per acre (gal/ac) and the amount of P2O5 and K2O that are applied (lb/ac). The impact of using constant values of Af and mf that are different from values that more closely match the data was studied by comparing the results for spreading lagoon water (TS = 0.5%) and slurry (TS = 7.5%) to meet a target application rate of 100 lb PAN/ac. The results are provided in Table 3. The impact of settling and biological treatment in the lagoon was indicated by the low TS content (TS=0.5%) and the fact that the lagoon water contained two pounds of TAN for every pound of organic-N. Swine slurry (TS = 7.5%) contained 1.2 pounds of TAN per pound of organic-N.

Comparison of the estimates using Clemson Extensions current recommendations with the results provided in this paper led to the following observations.

    • Using the new Af and mf values that varied by manure type (lagoon water vs slurry) provided higher PAN estimates than the Clemson Extension recommendations.
    • The higher PAN estimates resulted in reductions in the amount of manure needed to provide 100 lb PAN/ac.
    • The amount of ammonia-N lost per acre per 100 lb PAN applied was much lower using the new factors for estimating PAN as compared to using Clemson Extension values for lagoon water and swine slurry. Using Clemson Extension values over-estimated the ammonia-N loss/ac by 133% to 1133%.
    • The inaccuracies in PAN estimates for lagoon water and slurry manure also impacted plant nutrient application rates. Using the PAN estimates based on Clemson Extension recommendations to determine manure application rates resulted in over application of nitrogen by 17% to 21%. Similar over-applications were observed for P2O5 and K2 Therefore, better estimates of PAN can help to reduce excessive applications of phosphorous and provide better estimates of potash (K2O) application rates.
    • Comparison of the estimates of the ammonia-N lost per acre following broadcast of manure for the examples shown in Table 4 demonstrates the need to consider using values of Af and mf that more closely agree with the available data.
    • It must be emphasized that slurry manure with a higher TS content than 7.5% and heavily bedded manure were not included in the examples in this paper. The ammonia-N loss values will be higher and must be calculated using the Af values provided in this paper along with the corresponding manure analysis to yield valid conclusions.

Impact of Selected Ammonium-N Conserving Application Methods on Ammonia-N Loss per Acre, and P2O5 Application Rate

The impact of application method on the estimates of PAN, ammonia-N loss, and phosphorous application rates was calculated for swine slurry using the tabulated values for the ammonium-N availability factors given in Table 2.  Lagoon water was not included because irrigation is the most common and cost-effective method of application, and the amount of ammonia-N lost to the air was the least. The application methods that were compared were broadcast, broadcast followed by incorporation within 6 hours, band spreading, band spreading with shallow soil cover, and shallow injection. Results for deep injection were not included because the improvements were very small compared with shallow injection (see Table 2). Furthermore, the horsepower and fuel costs of deep injection are higher than for shallow injection. The results are given in Table 4.

The results indicated that broadcast with incorporation within 6 hours provided a reduction in ammonia-N loss per acre of 65% and a reduction in the P2O5 application rate of 11%. Band spreading provided almost the same benefits (57% reduction in ammonia-N loss and 10% reduction in lb P2O5/ac) but would be achieved with only one pass across a field. Adding a method to immediately cover a band of manure with soil provided reductions in ammonia-N loss of 90% and reduction of the P2O5 application rate by 16%. Shallow injection provided a modest improvement in ammonia-N emissions (93%) as compared to band spreading with shallow cover. Shallow injection also provided about the same benefit in reduction of phosphorous application rate as band spreading with shallow cover.

 

Table 3. Comparison of land application rate and ammonia-N loss estimates using tabulated model results and current Clemson University Extension recommendations for broadcast application of swine lagoon surface water and slurry manure. Target nutrient application rate = 100 lb PAN/ac.
Swine
Lagoon Water Slurry
TS, % 0.5 7.5
TAN, lb/1000 gal 4.3 23.0
Org-N, lb/1000 gal 2.0 19.0
P2O5, lb/1000 gal 3.6 33.0
K2O, lb/1000 gal 7.9 28.0
Land Application Rates and Ammonia-N Loss Estimates Using Clemson Extension Recommendations
Mineralization factor, mf 0.60 0.60
Ammonium-N availability factor, Af 0.80 0.50
PAN estimate, lb PAN/1000 gal 4.6 22.9
Application rate to provide 100 lb PAN/ac, gal/ac 21,552 4,367
Resulting application rate for P2O5, lb/ac 78 144
Resulting application rate for K2O 170 122
Ammonia-N Loss, lb per acre / 100 lb PAN 18.5 50.2
Land Application Rates and Ammonia-N Loss Estimates Using New Recommendations
Mineralization factor, mf 0.70 0.50
Ammonium-N availability factor, Af 0.98 0.75
PAN estimate, lb PAN/1000 gal 5.6 26.8
Application rate to provide 100 lb PAN/ac, gal/ac 17,813 3,738
Resulting application rate for P2O5, lb/ac 64 123
Resulting application rate for K2O 141 105
Ammonia-N Loss, lb per acre / 100 lb PAN 1.5 21.5
Key Impacts of Inaccurate Estimates of Af, and PAN
Over-estimation of Ammonia-N Loss/ac 1133% 133%
Actual PAN Application Rates Using Clemson Extension Recommendations to Determine Manure Application Rate, lb PAN/ac and percent over-application of PAN (%) 121
(21%)		 117
(17%)
Difference in Application of P2O5, lb/ac (%) 14
(22%)		 21
(17%)
Difference in Application of K2O, lb/ac (%) 29
(21%)		 17
(14%)

 

Table 4. Impact of Application Method on Ammonia-N Loss and P2O5 Application Rate for Swine Slurry. The total solids and plant nutrient contents were given previously in Table 3 and the mineralization factor was 0.50 for all application methods.
Swine
Slurry, TS = 7.5%
Broadcast – no incorporation
Mineralization factor, mf 0.50
Ammonium-N availability factor, Af 0.75
PAN estimate, lb PAN/1000 gal 26.8
Application rate to provide 100 lb PAN/ac, gal /ac 3,738
Resulting application rate for P2O5, lb/ac 123
Ammonia-N Loss, lb per acre / 100 lb PAN 21.5
Broadcast – incorporation within 6 hours
Ammonium-N availability factor, Af 0.90
PAN estimate, lb PAN/1000 gal 30.2
Application rate to provide 100 lb PAN/ac, gal /ac 3,311
Resulting application rate for P2O5, lb/ac 109
Ammonia-N Loss, lb per acre / 100 lb PAN 7.6
Reduction in Ammonia-N loss Compared to Broadcast 65%
Reduction in P2O5 Application Rate 11%
Band Spreading
Ammonium-N availability factor, Af 0.88
PAN estimate, lb PAN/1000 gal 29.7
Application rate to provide 100 lb PAN/ac, gal /ac 3,362
Resulting application rate for P2O5, lb/ac 111
Ammonia-N Loss, lb per acre / 100 lb PAN 9.3
Reduction in Ammonia-N loss Compared to Broadcast 57%
Reduction in P2O5 Application Rate 10%
Band Spreading with Shallow Cover
Ammonium-N availability factor, Af 0.97
PAN estimate, lb PAN/1000 gal 31.8
Application rate to provide 100 lb PAN/ac, gal /ac 3,144
Resulting application rate for P2O5, lb/ac 104
Ammonia-N Loss, lb per acre / 100 lb PAN 2.2
Reduction in Ammonia-N loss Compared to Broadcast 90%
Reduction in P2O5 Application Rate 16%
Shallow Injection
Ammonium-N availability factor, Af 0.98
PAN estimate, lb PAN/1000 gal 32.0
Application rate to provide 100 lb PAN/ac, gal /ac 3,121
Resulting application rate for P2O5, lb/ac 103
Ammonia-N Loss, lb per acre / 100 lb PAN 1.4
Reduction in Ammonia-N loss Compared to Broadcast 93%
Reduction in P2O5 Application Rate 17%

Future Plans

The model results provided in this paper are currently being used to develop extension programs and will be used to update extension publications and recommendations for producers. It is hoped that these tabulated ammonium-N availability factors will be used to increase the precision of using swine manure as a fertilizer substitute and making better estimates of ammonia-N emissions.

Author

John P. Chastain, Professor and Extension Agricultural Engineer, Agricultural Sciences Department, Clemson University

Corresponding author email address

jchstn@clemson.edu

Additional Information

CAMM. 2005. Confined Animal Manure Managers Program Manual – Swine Version. Clemson, SC.: Clemson University Extension. Available at https://www.clemson.edu/extension/camm/manuals/swine_toc.html.

Chastain, J.P. 2006. A Model to Estimate Ammonia Loss Following Application of Animal Manure, ASABE Paper No. 064053. St. Joseph, Mich.: ASABE.

Chastain, J. P., J. J. Camberato, and J. E. Albrecht. 2001. Nutrient Content of Livestock and Poultry Manure. Clemson, SC.: Clemson University.

Montes, F. 2002. Ammonia volatilization resulting from application of liquid swine manure and turkey litter in commercial pine plantations. MS Thesis, Clemson, SC.: Clemson University.

Montes, F., and J.P. Chastain. 2003. Ammonia Volatilization Losses Following Irrigation of Liquid Swine Manure in Commercial Pine Plantations. In Animal, Agricultural and Food Processing Wastes IX: Proceedings of the Nineth International Symposium, 620-628. R.T. Burnes, ed. St. Joseph, Mich.: ASABE.

USEPA. 1995. Control and Pollution Prevention Options for Ammonia Emissions (EPA-456/R-95-002), report prepared by J. Phillips, U.S. Environmental Protection Agency, Control Technology Center. Research Triangle Park, NC. Available at https://www.epa.gov/sites/default/files/2020-08/documents/ammoniaemissions.pdf.

 

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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Closing the Loop: Evaluating Carcass Compost for Corn Production in Northern Climates

Purpose

Composting is one way that livestock operations can effectively dispose of animal carcasses on their farm site during many times of the year, even in cold climates. Various carbon sources such as wood chips or chopped corn stalks can be used and tend to be coarsely chopped so that airflow is improved through the pile to increase degradation. This makes finished carcass compost different from typical manure or garden compost. Land application is recommended for the final product, but there is little information on nutrient availability of carcass compost for crop production. Since state regulations often require this information to determine appropriate agronomic land application rates, livestock producers are left unable to utilize this material efficiently in a way that meets the law. The goal of this project is to evaluate the fertilizer equivalent value of carcass compost that uses different carbon sources (wood chips versus corn stalks) for corn production.

What Did We Do

The Minnesota Department of Agriculture conducted winter swine carcass composting trials at the University of Minnesota Southwestern Research and Outreach Center in Lamberton, MN during the winter of 2020. In these trials, swine carcasses were ground with the carbon source prior to initiating the compost process. Carbon sources included wood chips or corn stalks. The compost went through the active composting cycles (thermophilic phase) and curing (mesophilic) phase over approximately one year. Samples were collected from each pile in the spring of 2021 and sent to Penn State Analytical Laboratory for standard compost tests.

In 2021, a field experiment was carried out at the University of Minnesota Southwestern Research and Outreach Center in Lamberton, MN to test the different carcass composts as a nutrient source. The field trial was set up as a randomized complete block design with four replications as the blocks. The 10 treatments included:

  • 0 N (full P, K, S) fertilizer (control)
  • 3 urea fertilizer N rates (50%, 100%, 150% of corn nitrogen [N] needs)
  • 3 woodchip compost and 3 corn stalk compost rates (50%, 100%, 150% of corn N needs)

The compost rates were determined assuming 50% of the total N from lab analysis is plant available. The overall N rates were determined using the University of Minnesota fertilizer guidelines for non-irrigated corn. Fertilizers and compost were applied by hand in spring at their appropriate rates and incorporated within 12 hours of application. Approximately 7, 14, and 21 tons per acre of compost were applied to achieve 50%, 100%, and 150% of corn N needs (this corresponds to 80, 160, and 240 pounds of N per acre). Corn was planted and managed for pests according to typical production practices in the region. The middle two rows of each plot were harvested in the fall with a plot combine and yield and grain moisture were recorded.

What Have We Learned

The lab analysis results of each compost are in Table 1. Total N content was similar between sources and primarily made up of organically bound N. The carbon:N ratio of the wood chip compost was higher at 20.8:1 than the corn stalk compost at 14.2:1, though both were below 20:1 and should not theoretically tie up N from the soil after land application. Respirometry tests suggested that the corn stalk compost was not yet mature (respiration was greater than 11 mg CO2-C/g organic matter/day) while the wood chip compost was considered in the “curing” phase (2-5 mg CO2-C/g organic matter/day). The bioassay results suggested that neither compost had any phytotoxins (both had emergence greater than 90%).

Table 1. Swine carcass compost test results from Penn State Analytical Laboratory. Samples were collected and sent to the lab in spring 2021 prior to land application.

Carcass Compost Carbon Source
Tests Wood Chips Corn Stalks
pH 7.3 8.0
Soluble salts (1:5 w:w), mmhos/cm 1.2 2.5
Moisture content, % 29.1 41.2
Organic matter, % 49.1 33.4
Total nitrogen (N), lb ton-1 22.0 24.0
Organic N, lb ton-1 22.0 22.0
Ammonium-N, lb ton-1 0.32 0.66
Nitrate-N, lb ton-1 0.04 0.00
Carbon: N ratio 20.8 14.2
Phosphorus (as P205) lb ton-1 5.4 4.6
Potassium (as K20) lb ton-1 6.6 9.4
Particle Size (<9.5 mm), % 82.6 68.1
Respirometry, mg CO2C/g organic matter/day 4.8 17.4
Bioassay (cucumber seedling emergence), % 100.0 96.0
Bioassay (cucumber seedling vigor), % 100.0 100.0

As for the field trial, the 2021 growing season endured a sustained drought and yield was lower than expected (ranging from 64 – 117 bushels per acre; Figure 1). Yield increased with each incremental increase in fertilizer N with the highest yield at 240 pounds of N per acre. The carcass composts differed in their effect on yield. Corn yield responded to the corn stalk compost and fertilizer up to 150 pounds of available N per acre (or about 14 tons per acre), but the carcass compost reduced yield at 240 pounds of N per acre. Yield only responded to the wood chip compost at the lowest rate (80 pounds of N per acre, or about 7 tons per acre) but at higher rates yield was similar to the control. This is likely due to the high carbon content of both composts. As more carbon was applied, the soil microbes needed a higher amount of N to degrade the carbon, thus taking it from the soil. Overall, we suggest that less than 15 tons per acre of carcass compost should be used for land application. If wood chips were used as the carbon source, do not expect a significant nitrogen credit.

Figure 1. Corn yield with fertilizer versus swine carcass compost (with either corn stalks or wood chips as the carbon source). Each nutrient source was applied at different rates to supply 80, 160, or 240 pounds of first year available nitrogen. There was also a no-nitrogen control.

Future Plans

We will repeat this study in 2022 at the same site but with compost generated during the winter of 2021. Besides wood chips and corn stalks, a new carbon source will be introduced to the project, wheat straw. Along with yield, we are also evaluating soil and plant samples for nitrogen and phosphorus changes.

Authors

Melissa L. Wilson, Assistant Professor and Extension Specialist, University of Minnesota
mlw@umn.edu

Additional Authors

-Erin L. Cortus, Associate Professor and Extension Engineer, University of Minnesota;
-Paulo H. Pagliari, Associate Professor, University of Minnesota

Acknowledgements

This project is funded by USDA’s Animal and Plant Health Inspection Service through the National Animal Disease Preparedness and Response Program. Thanks to our partners at the Minnesota Department of Agriculture for supplying the carcass compost.

 

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 Sludge on Nutrient Concentration in Anaerobic Swine Lagoon Supernatant

Purpose

The most common waste management practice on hog farms in Eastern North Carolina are anaerobic lagoons. Lagoons contain three zones: [1] sludge storage zone at the bottom, [2] treatment zone for incoming manure in near the middle, and [3] a liquid (supernatant) storage zone at the top. The supernatant is land applied throughout the year as a nutrient source for growing crops on farms while the middle (treatment) zone is required to remain full to ensure effective treatment.

Considering the risk that hurricanes pose to North Carolina and the hog sector (particularly during late summer months), close lagoon management is critical to avoid risk of overflow or breach. Currently, regulations allow swine growers to lower the effluent level in their lagoons by applying part of the treatment zone effluent. Conditional to this allowance, however, is that the treatment zone contains at least 4-feet of depth that is sludge-free. This condition aims to ensure applied effluent is safe for application.

While this condition is helpful to reducing the risk of applying higher concentration of phosphorus, zinc, and copper to crops, many producers do not meet this condition due to excessive sludge buildup and would not be able to lower the lagoon level which poses a significant risk during intense rainfall events.

This study aims to quantify the impact of the sludge-free depth in the lagoon on the quality of supernatant during the drawdown period. Findings will help with precision nutrient application from swine manure and allow for further drawdown during necessary storm events.

What Did We Do

This study used a dataset representing 27 swine operations in Eastern North Carolina between 2016-2021. The dataset includes:
1. Monthly effluent/waste sampling analysis,
2. Annual sludge surveys, as well as
3. Lagoon level readings.

This dataset was analyzed using statistical methods to quantify the impact of seasonality (time of year), farm type (sow, finisher, or farrowing), and sludge level on nutrient concentration in the effluent.

Most growers use depth, in inches, to report volumes applied or available for storage. However, when comparing lagoons with different designs, this can be a challenge. As such, we developed two parameters to facilitate cross-farm, cross-lagoon comparisons. The first is “freeboard ratio” (FBR), which refers to the relative “fullness” of the storage zone in the lagoon. FBR value between 0 and 1 indicates the lagoon is currently within the storage volume (between start and stop pumps), values greater than 1 indicate the lagoon is in drawdown, and negative values indicate the lagoon level exceeded the storage volume and is currently in the rainfall/storm storage zone and must be lowered promptly. The equation used to calculate FBR is as follows:

TBR= LFB-Lstart , variables defined in Figure 2.
Lstop-Lstart

The second variable is “sludge level ratio” (SLR), which refers to the relative treatment volume available compared to the 50% treatment volume required. SLR values greater than 1 indicate that more than 50% of the treatment volume is sludge-free in the lagoon and therefore drawdown can proceed, and no sludge removal is necessary. SLR values less than 1 indicate that less than 50% of the treatment volume is available and drawdown might not be feasible. The equation used to calculate SLR is as follows:

SLR= Lsludge-Lstop , variables defined in Figure 2.
L0.5. Trt-Lstop
Figure 2. Anaerobic lagoon zones used to calculate study parameters FBR and SLR

What Have We Learned

In analyzing the dataset we observed that only 2% of the samples were collected while the lagoon level exceeded storage level (above the start-pump level). This suggests the majority of studied operations were successful in managing effluent despite the wet years observed between 2016 and 2021. By comparison, 22% of the samples were collected while the lagoon was at a draw-down state (the entire storage volume is empty and the treatment zone is partially emptied).

Additionally, 38% of the samples collected were associated with lagoons that needed sludge removal (SLR < 1). These results are summarized in Table 1, with 12% of samples collected from lagoons in drawdown (FBR > 1) and in need of sludge removal (SLR < 1). This latter group of samples represent the primary concern for lagoon drawdown.

 

Table 1. Summary of FBR and SLR Interactions
Lagoon Sample Class Sludge Level Ratio (SLR)
No Removal Removal Due
Freeboard Ratio (FBR) Above stop-pump 40% 26%
In drawdown 22% 12%

The season was a significant predictor of the lagoon level (p < 0.001), with the late irrigation season (July – Sept) showing the least effluent volume in the lagoon. On average, 91% of the storage volume was unoccupied. This compares to the winter months (Oct – Feb) and the early irrigation season (Mar – June) with 81 and 69% of the storage volume empty, respectively.

For all seasons the mean ratio of N : P2O5 : K2O in the supernatant is 4 : 1 : 8.2. There was less variability for N and K content with the lagoon level than for P, Zn, and Cu. This can be attributed to the N and K being primarily in soluble forms in the lagoon supernatant compared to P2O5, Zn and Cu which are mostly bound to solids.

The analysis showed a greater variability in Zn, Cu, and P levels with changes in solid concentration in the supernatant as well as the amount of suspended solids as a result of wind or active lagoon agitation/sludge removal.

Overall, the results showed lagoon drawdown and existing sludge reserves to have a combined effect on nutrient concentrations in the supernatant, particularly for phosphorus.

Future Plans

This study will inform ongoing research to predict temporal variability in nutrient content in the lagoon due to weather, operational decisions, and time of year. Near term, these observations will help guide application rates to ensure P levels meet crop demands particularly during late-season drawdown without significantly increasing soil P levels. In addition, this work will be part of a larger study to predict the performance of anaerobic treatment lagoons under future climate conditions.

Authors

Presenting Author:
Carly Graves, Graduate Research Assistant, North Carolina State University

Corresponding Author:
Dr. Mahmoud Sharara, Assistant Professor & Waste Management Extension Specialist, North Carolina State University
msharar@ncsu.edu

Acknowledgements

Thank you to Smithfield Foods, Inc. for funding this research and providing datasets of sludge surveys.

Videos, Slideshows and Other Media

https://content.ces.ncsu.edu/sludge-sampling-in-anaerobic-treatment-swine-lagoons

 

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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Reduction and fate of manure pathogens and antimicrobial resistance

Antimicrobial resistance is a complex issue as it is comprised of not only pathogenic bacteria, but also non-pathogens which share genes within complex environmental systems, such as agricultural fields. This webinar describes potential measures to reduce pathogen and antimicrobial resistance in manure as well as potential fate and transport of manure pathogens and antimicrobial resistance following land application of manure. This presentation was originally broadcast on May 17, 2019. More… Continue reading “Reduction and fate of manure pathogens and antimicrobial resistance”

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

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Purpose

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

victor@farmfreezers.com

Other Authors

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

Additional Information

https://rendermagazine.com/wp-content/uploads/2019/07/Render_Oct16.pdf

Farm Freezer Biosecurity Benefits

One Night in a Composting Shed

www.farmfreezers.com

—

Transmission Pathways

Avian flu conditions still evolving (editorial)

USDA NRCS Conservation fact sheet Poultry Freezers

Nature.com 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)

Acknowledgements

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.

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Diet, Tillage and Soil Moisture Effects on Odorous Emissions Following Land Application of Beef Manure

 

Figure1.  Gas sampling equipment used during the study.

Waste to Worth: Spreading science and solutions logoWaste to Worth home | More proceedings….

Abstract

Little information is currently available concerning odor emissions following land application of beef cattle manure. This study was conducted to measure the effects of diet, tillage, and time following land application of beef cattle manure on the emission of volatile organic compounds (VOC).

Each of the experimental treatments which included tillage (broadcast or disked) and diet (0, 10, or 30% wet distillers grain (WDGS)) were replicated twice. A 5-m tandem finishing disc was used to incorporate the manure to a depth of approximately 8 cm.  Small plots (0.75 m x 2.0 m) were constructed using 20 cm-wide sheet metal frames. A flux chamber was used to obtain air samples within the small plots at 0, 1, 2, 6, and 23 hours following manure application. The flux of fifteen VOC including fatty acids, aromatic compounds, and sulfur containing compounds were measured. Based on odor threshold, isolavleric acid, butyric acid, and 4-methylphenol provided 28.9%, 18.0%, and 17.7%, respectively, of the total measured odor activity. Heptanic acid, acetic acid, skatole, 4-methyphenol, and phenol each contributed less than 1% of the total odor activity. Dimethy disulfide (DMDS) and dimethyl trisulfide were the only measured constituents that were significantly influenced by diet.

DMDS values were significantly greater for the manure derived from the 30% WDGS diet than the other manure sources. No significant differences in DMDS values were found for manure derived from diets containing 0% and 10% WDGS. Tillage did not significantly affect any of the measured VOC compounds. Each of the VOC was significantly influenced by the length of time that had expired following land application. In general, the smallest VOC measurements were obtained at the 23 hour sampling interval.  Diet, tillage, and time following application should each be considered when estimating VOC emissions following land application of beef cattle manure.

Why Study Factors Affecting Manure Application Odors?

Measure the effects of diet, tillage and soil moisture on odor emissions follow land applied beef manure.

Figure 2.  Relative contribution of odorant to the total odor activity.

What Did We Do?

Twelve plots were established across a hill slope. Treatments were tillage (broadcast or disked) and diet (0%, 10%, or 30% WDGS).  Beef manure was applied at 151 kg N ha-1 yr-1.  Gas samples were collected using small wind tunnels and analyzed using a TD-GC-MS. (Fig. 1).  VOC samples were collected at 0, 1, 2, 6, and 23 hours following manure application.  A single application of water was applied and the gas measurement procedure was repeated. The effects of tillage, diet, test interval, and the sample collection time on VOC measurements were determined using ANOVA (SAS Institute, 2011).

What Have We Learned?

Isovaleric acid, butyric acid, and 4-methylphenol accounted for 28.9%, 18.0%, and 17.7%, respectively of the total odor activity (Fig. 2). Dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) emissions were significantly increased by the 30 % WDGS diet. The flux increase for DMDS was over 4 times greater for the 30% WDGS diets. Tillage did not significantly affect any of the measured VOC compounds. The largest propionic, isobutric, butyric, isovaleric, and valeric acid measurements occurred with no-tillage under dry condition (Fig. 3A-E). Generally, measured values for these constituents were significantly greater at the 0, 1, 2, and 6 hour sampling intervals than at the 23 hour interval (Fig. 3A-E). The larger emissions for no-till, dry conditions may be due to the drying effect resulting when the manure was broadcast on the surface.  As the manure begins to dry, the water soluble VOCs are released from solution.  The tilled and wet conditions would reduce its release of VOC due to the increased moisture conditions.

Figure 3. Flux values for propionic, isobutyric, butyric, isovaleric , valeric acid and indole as affected by tillage, soil moisture, and time.

Future Plans

Additional studies are planned to quantify the moisture and temperature effect on odorous emissions.

Authors

Bryan L. Woodbury, Research Agricultural Engineer, USDA-ARS,  bryan.woodbury@ars.usda.gov

John E. Gilley, Research Agricultural Engineer, USDA-ARS;

David B. Parker, Professor and Director, Commercial Core Laboratory, West Texas A&M University;

David B. Marx, Professor Statistics, University of Nebraska-Lincoln;

Roger A. Eigenberg, Research Agricultural Engineer, USDA-ARS

Additional Information

http://www.ars.usda.gov/Main/docs.htm?docid=2538

Acknowledgements

We would like to thank Todd Boman, Sue Wise, Charlie Hinds and Zach Wacker for their invaluable help on making this project a success.

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. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

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On-Farm Nutrient Management Research: Replacing Commercial Sidedress Nitrogen with Liquid Livestock Manure on Emerged Corn

This webinar highlights the on-farm research that has been done and is being planned in the state of Ohio to capitalize on the opportunity to apply in-season nutrients with manure application. This presentation was originally broadcast on May 19, 2017. More… Continue reading “On-Farm Nutrient Management Research: Replacing Commercial Sidedress Nitrogen with Liquid Livestock Manure on Emerged Corn”

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