Tag: nutrient management

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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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Characterization of Innovative Manure Treatment Components

Purpose

Improvements in manure treatment/nutrient management are an important need for dairy farms to move substantively towards sustainability. This project quantifies several individual manure treatment components and component assemblies targeted to address farm/environment needs. Project outcomes should help dairy farms to make better-informed decisions about manure/nutrient management systems.

Societal demand for farms to reduce their environmental impact is driving the need for improved and cost-effective manure/nutrient management options. Dairy farms may need advanced manure treatment systems to be economically, environmentally, and societally sustainable.

What Did We Do?

Specific treatments being evaluated include anaerobic digestion, active composting, sequencing batch reactors, solid-liquid separation systems including, screw press separation, dissolved air floatation, centrifuging, and solid treatment systems including bedding recovery units and pelletization. We are working with a farm that has an anaerobic digester and screw press separators. They have been planning to install a Dissolved Air Flotation (DAF) system. The farm was approached with an in-vessel composting technology “active composting” to determine if it could effectively convert portions of the digested separated liquid flow to a stabilized solid that could be pelletized and exported, while the liquids could be further treated to become dilute enough to be spray irrigated on a limited acreage.

What Have We Learned?

We learned that although the active composting process was able to quickly produce stabilized high solid content material from a variety of mixes of digested separated liquid and dried shavings, the energy needed ranged from $9 to $14 per cow per day. Through volume/time calculations, the pumping system from the reception pit to the digester and the post digestion pit to the separators varied although the % solids were consistent. Doppler flow meters purported to be able to measure manure did not give consistent volume results. Screw press solid liquid separation can result in a bedding product with relatively low moisture (60%) from anaerobically digested dairy manure.  Determining an optimum manure treatment system for dairy manure will be difficult given the variability from farm to farm.

Future Plans

Specific treatments yet to be evaluated include: anaerobic sequencing batch reactors, solid liquid separation systems including dissolved air floatation (DAF), centrifuging, and solid treatment systems including bedding recovery units (BRU) and pelletization. Covid supply chain issues and travel restrictions have slowed progress. The DAF system can be directly analyzed as it is installed on the dairy. A neighboring farm has a BRU that will be sampled and analyzed. Data from a centrifuge and pelletizer will be obtained from the literature. Putting the process in a treatment train will be explored on a spreadsheet.

Authors

Peter Wright, Agricultural Engineer, PRO-DAIRY, Cornell University

Corresponding author email address

pew2@cornell.edu

Additional authors

Lauren Ray, Environmental Energy Engineer, PRO-DAIRY, Cornell University
Curt Gooch, Emeritus Senior Extension Associate, Cornell University

Additional Information

We have completed several fact sheets including Manure Basics, Advanced Manure Treatment – Part 1:  Overview, Part 2:  Phosphorus recovery technologies, Part 3:  Nitrogen recovery technologies, and Part 4:  Energy extraction. These are available at: https://cals.cornell.edu/pro-dairy/our-expertise/environmental-systems/manure-management/manure-treatment

Publications: Peter Wright, Karl Czymmek, and Tim Terry “Food waste coming to your farm? Consider where the nutrients go and manure processing for nutrient export” PRO-DAIRY The Manager, contained in Progressive Dairy Vol. 35 No. 5 March 12, 2021

Acknowledgements

This work was supported by a joint research and extension program funded by the Cornell University Agricultural Experiment Station (Hatch funds) and Cornell Cooperative Extension (Smith Lever funds) received from the National Institutes for Food and Agriculture (NIFA,) U.S. Department of Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.  New York State Pollution Prevention Institute (NYSP2I) at the Golisano Institute for Sustainability (GIS) paid for the sampling that was funded by a grant to RIT from by the Environmental Protection Fund as administered by the NYS Department of Environmental Conservation.

 

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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Does Irrigation of Liquid Animal Manure Increase Ammonia Loss?

Purpose

Large bore traveling gun and center pivot irrigation systems have been used to apply treated lagoon effluent, liquid animal manure, and untreated slurry from swine and dairy farms in many parts of the USA. The primary advantage of using irrigation equipment to spread manure on cropland are the lower costs for energy and labor, and the higher speed of application as compared to using a tractor-drawn spreader. The primary disadvantages are related to increases in odor release and the possibility of spraying manure on roads or another person’s property.

Ammonia-N loss from land application of manure is important because it is a loss of fertilizer nitrogen, and it is a source of air pollution. A previous study and several extension publications state that irrigation of animal manure increases ammonia-N loss by 10% to 25% (Chastain, 2019). As a result, the total ammonia-N loss was the sum of the ammonia-N lost while the manure traveled from the irrigation nozzle to the ground and the ammonia-N lost as the manure released ammonia-N after striking the ground.

The objective of this presentation is to summarize the results of a meta-analysis of 55 data sets from 3 independent sources to quantify the ammonia-N lost during the interval of time from when the liquid manure exited the irrigation equipment and when a sample was collected on the ground. The complete review, data analysis, and the data used were provided by Chastain (2019).

What Did We Do?

The study included data from traveling gun, center pivot, and impact sprinkler irrigation of untreated liquid and slurry manure, lagoon supernatant, and effluent from an oxidation ditch. The data sets included measurements of the total solids content (TS, %), total ammoniacal N concentration (TAN = ammonium-N + Ammonia-N), and total nitrogen (TKN) for a sample collected from the lagoon or storage to describe what was in the manure that left the irrigation nozzle and measurements of the TS, TAN and TKN in the samples that were collected from containers on the ground. The concentrations of TS, TAN, and TKN in the ground collected manure samples were plotted against the TS, TAN, and TKN concentrations in the irrigated manure. The data pairs were analyzed using linear regression to determine if there was a statistically significant difference between the irrigated and ground collected samples. If there was perfect agreement the slope of the line would be 1.0. Therefore, statistical tests were used to determine if the slope of the line was statistically different from 1.0. If the test indicated that the slope was not significantly different from 1.0 then irrigation did not change the concentration of the TS, TAN, or TKN.

What Have We Learned?

Well-known data used in irrigation design indicates that evaporation loss during irrigation ranges from 1% to 3.5%. The plot of the data for irrigated manure is shown in Figure 1. It was determined that the slope of the regression line was statistically greater than 1.0. Therefore, evaporation losses were small, 2.4%, and agreed with previous studies on irrigation performance.

Figure 1. Comparison of the total solids content of the irrigated manure and the samples collected on the ground indicated that evaporation losses were 2.4%.

The plot of the TAN concentrations collected on the ground and the TAN contained in the irrigated water is shown in Figure 2.). The results showed that irrigation of manure did not result in a change in the concentration of TAN. Therefore, irrigation of manure did not cause ammonia-N loss.

The same type of analysis was done for the total nitrogen data to serve as check on the TAN results. As expected, the analysis showed that irrigation did not significantly alter the concentration of TKN.

Figure 2. The concentration of the total ammoniacal nitrogen was not changed as the manure traveled through the air. This was indicated by a regression line slope that was not significantly different from 1.0.

A previous study reported TAN losses ranging from 10% to 25% during irrigation of liquid manure. Error analysis of the techniques used in these studies indicated that most of the average ammonia-N loss predicted was due to volume collection error in the irrigate-catch technique that was used, and not evaporation and drift as was assumed (see Chastain, 2019). It was concluded that irrigation, as a manure application method, did not increase ammonia-N losses. These results do not imply that ammonia volatilization after manure strikes the ground is to be ignored. The suitability of irrigation as a liquid manure application method should be evaluated based on the level of treatment and the potential impact of odors on neighbors.

Future Plans

These results are being used in extension programs and to help refine estimates of ammonia-N loss associated with land application of manure.

Author

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

Corresponding author email address

jchstn@clemson.edu

Additional Information

Chastain, J.P. 2019. Ammonia Volatilization Losses during Irrigation of Liquid Animal Manure. Sustainability 11(21), 6168; https://doi.org/10.3390/su11216168.

 

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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Overview of ODA’s Division of Livestock Environmental Permitting

Purpose

The purpose of this presentation is to provide a complete overview of ODA’s Division of Livestock Environmental Permitting (“ODA-DLEP”). ODA-DLEP regulates any livestock facility in Ohio that has the following number of animals or greater:

    • 700 mature dairy cows
    • 1,000 beef cattle or dairy heifers
    • 2,500 swine weighing more than 55 pounds
    • 10,000 swine weighing less than 55 pounds
    • 82,000 layers
    • 125,000 broilers or pullets
    • 500 horses
    • 55,000 turkeys

What Did We Do

Ohio Department of Agriculture’s Division of Livestock Environmental Permitting (“ODA-DLEP”) regulates the siting, construction, and operation of Ohio’s largest livestock facilities, referred to as Concentrated Animal Feeding Facilities (“CAFF”). ODA-DLEP’s primary objective is to minimize any water quality impacts, including both surface and ground waters, associated with the construction of new or expanding CAFFs, as well as implementation of best management practices once a CAFF becomes operational. These best management practices include management of manure, insect and rodent control, mortality management, and emergency response practices. ODA-DLEP issues Permits to Install (for construction) and Permits to Operate (for operations).

In addition, ODA-DLEP conducts routine inspections of each CAFF at least once a year, responds to complaints, and participates in emergency response. Inspections are conducted to review a CAFF’s compliance with Ohio Revised Code 903 and Ohio Administrative Code 901:10, the laws and regulations governing Concentrated Animal Feeding Facilities.

Finally, ODA-DLEP administers the Certified Livestock Manager program. Any individual in the State of Ohio that manages 4,500 dry tons of solid manure or 25 million gallons of liquid manure is required to be a Certified Livestock Manager (“CLM”).

What Have We Learned

Livestock operations continue to get larger and more concentrated and as a result, regulations are necessary to ensure proper handling and management of manure, particularly with land application of manure.

Future Plans

Over the past several years, DLEP has started to see more interest in manure treatment technologies. This could include, but is not limited to, anaerobic digestion, nutrient recovery, solids separation, and wastewater treatment. Technologies like this could greatly alter the landscape of the livestock industry by fundamentally changing the way manure is handled and how nutrients from manure are applied. DLEP does have regulations in place to account for manure treatment technologies. However, regulations, and specifically changes to regulations, cannot maintain the same pace as these technological advancements.

Authors

Samuel Mullins, Chief of ODA-Division Livestock Environmental Permitting
Samuel.mullins@agri.ohio.gov

Additional Information

https://agri.ohio.gov/divisions/livestock-environmental-permitting
https://codes.ohio.gov/ohio-administrative-code/901:10
https://codes.ohio.gov/ohio-revised-code/chapter-903

Videos, Slideshows and Other Media

ODA Division Spotlights – Division of Livestock Environmental Permitting 1

ODA Division Spotlights – Division of Livestock Environmental Permitting 2

 

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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Experience of Removing and Land Application of Lagoon Solids

Purpose

Manure lagoon systems are designed to hold and treat animal farm wastewater for a predetermined period and remain popular in many livestock farms. If the lagoon is properly designed and built, many years can go by without any significant maintenance requirements outside of water management, pumps and valves. Depending on the capacity and maintenance, additional manure solid removal is often required to reduce the amount of manure solids entering the lagoon storage. When excessive solids build-up or sludge was found, significant odor and low quality/quantity of flushing water would be the issues.

This study documents experience to prepare for and complete land application of lagoon effluent with heavy solids from a flush dairy lagoon in central Missouri. The free stall barn uses mattress bedding with supplemental cedar shavings and houses 140-160 lactating cows. Preparation included measuring lagoon sludge depth and lab analysis of sludge characteristics and scouting for crop fields for land application prior to contacting contractors for a bidding process. A contractor team utilized specialized equipment to dilute, agitate, pump and land apply approximately 8 million gallons of diluted lagoon solids in less than nine working days. Lagoon effluent was sampled throughout the process to monitor the mass of nutrients applied to specific plots of land. For effective lagoon solids removal and land application, proper preparation, specialty equipment and trained professional, timing of the crop fields, and adequate field working days are critical. Simple, non-mechanical technologies are available for even small to midsize dairy farms to reduce the cost of lagoon maintenance by preventing the bulk of solids from entering the lagoon.

What Did We Do?

We documented the process of lagoon solids removal for land application, considering the preparation (sludge and effluent sampling), specialty equipment and trained professionals, timing of the crop fields, and adequate field working days. The barn was flushed two to three times per day, with three times per day being typical. There was, at one time, an elevated screen that helped remove the large solids from the flush, but the screen system fell into disrepair several years ago and was abandoned. Solids in the lagoon were agitated and pumped out from May 21, 2020, through June 8, 2020, Figures 1 and 2. A total of 8 million gallons over 280 acres was applied to fields further away from the lagoon, including neighbor’s crop fields that were 1.5 miles away. Equipment needs and specifications were documented (Canter et al., 2021) and being prepared for an Extension publication.

Figure 1. PTO-drive lagoon agitators and agitation boat in operation.
Figure 2.  A dilution pump was used to pump water from the nearby lake (left) to the dairy lagoon (right) with agitation boat and lagoon agitation working in the background.

Daily lagoon effluent samples were taken multiple samples throughout the day on June 2 to gauge the consistency of nutrient concentrations. Results suggest that once completely mixed via agitation, the applied nutrient concentration from a single sample is a reliable estimate within a working day if the moisture content is consistent. The initial slurry had a 10-13 percent solids content, so a significant amount of dilution water was needed to dilute the solids content to the target range. The exact amount of dilution water used was unknown. Figure 3 shows the concentration and moisture data. In general, the higher the moisture content (less solids) in the slurry samples, the higher the concentrations of the important manure nutrients are. The team evaluated potential technologies based on historical experience and first-person interviews. A pull-plug sediment basin (PPSB) was selected after reviewing cost and visiting with a farmer who operated a PPSB and was satisfied with the overall operation and performance (Canter et al., 2021). The application rate of important manure nutrients did show variation during the several days of land application, suggesting an improvement to the real-time effluent nutrient measurement and land application rate adjustment could be improved to provide more consistent nutrients to the crop fields.

Figure 3. Concentrations and moisture content of slurry samples from the lagoon.

What Have We Learned?

Manure management can be a burden for animal feeding operations, which can potentially become a significant threat to the profitability and management of farms if not proactively managed. Owners would be well-advised to survey their lagoon yearly to track solid inventory and plan ahead for the amount of land needed for solids application. Proper solids removal from the lagoon, particularly if regular and effective solids removal has been neglected, requires specialized equipment to reduce liquid supernatant on an annual or semiannual basis. There can be significant variability of nutrient concentration and resulting mass applied. Testing for nutrient concentrations in the lagoon, whether supernatant or sludge, or both, can be misleading due to variance in concentrations due to moisture content as the applicators dilute and concentrate the solids during the land application process.

Daily sampling during land application could help but may not be practical due to the analysis time generally required by labs (5-10 business days). Sensors and probes are available that return instantaneous values and have been used in municipal and industrial wastewater treatment for over a decade. Companies have offered integrated sensors for land application equipment, combining them with their GPS and flow control system to give a complete and accurate summary of nutrient application. Simple, non-mechanical technologies are available for even small to midsize dairy farms to reduce the cost of lagoon maintenance by preventing the bulk of non-degradable solids from entering the lagoon. Implementation of a coarse solids separation system such as the PPSB could significantly reduce the long-term cost of manure management by allowing the operator to use more common equipment (e.g., a loader and spreader) to remove solids from the manure management system.

Future Plans

Continuous monitoring of the lagoon sludge level at a minimum of annual basis is needed to closely monitor the lagoon solid accumulation and performance of the PPSB. The authors are collaborating with NRCS team to improve the PPSB and ways to monitor the lagoon sludge level.

Authors

Teng Lim, Extension Professor, Agricultural Systems Technology, University of Missouri

Corresponding author email address

Limt@missouri.edu

Additional authors

Timothy Canter, Extension Specialist, Agricultural Systems Technology, University of Missouri

Joseph Zulovich, Extension Assistant Professor, Agricultural Systems Technology, University of Missouri

Additional Information

    1. Canter, T., Lim, T.-T., and J. A. Zulovich. 2021. Field Experience of Removing and Land Application of Dairy Lagoon Solids. In International Symposium on Animal Environment and Welfare. Rongchang, Chongqing, China.
    2. Lim, T.-T. 2022. Lagoon Solids Removal, Lessons Learned. Cleanout for Lagoons and Anaerobic Digesters, Jan 21, 2022. Webinar of Livestock and Poultry Environmental Learning Community (LPELC). https://lpelc.org/cleanout-for-lagoons-and-anaerobic-digesters/
    3. Canter, T., Lim, T.-T., Chockley, T. 2021. Considerations of Pull-Plug Sedimentation Basin for Dairy Manure Management. University of Missouri Extension Publication. Retrieved September 25, 2021. https://extension.missouri.edu/publications/eq302.

Acknowledgements

USDA NIFA, Water for Food Production Systems Program A9101, for supporting the project. It is titled “Management of Nutrients for Reuse”, a multi-faceted project that involves professionals from the University of Arkansas, University of Nebraska, Colorado School of Mines and Metallurgy, Case Western University, and University of Missouri.

Joe Harrison, Professor, Livestock Nutrient Management program, Washington State University

Gilbert Miito, Postdoctoral Fellow, Agricultural Systems Technology, University of Missouri

Richard Stowell, Biological Systems Engineering, University of Nebraska

Farm crew and custom applicator team for their help.

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A Transportation Simulation Model for selected Concentrated Animal Feeding Facility (CAFFs) within the Maumee Watershed, Ohio

Purpose

The goal of this study was to identify areas that were prone to nutrient transport from land application of manure-based on environmental conditions including length of streams and flood hazard potential in those areas. Additionally, the study aimed at developing an economic utility for producers in transporting manure in the Maumee Watershed in North-west Ohio targeted at reducing the potential environmental impacts that may arise from over application.

What Did We Do?

The initial basic feasible solution of the Hitchcock transportation model (Derigs, U. 1988. The Hitchcock Transportation Problem. In: Programming in Networks and Graphs. Lecture Notes in Economics and Mathematical Systems, vol 300. Springer, Berlin, Heidelberg.) was used to simulate the distribution of manure from 31 dairy and swine concentrated animal feeding facilities to agricultural census block groups (soybeans and corn) in the Maumee Watershed within NW Ohio. The model considered the supply and demand capacity of nearby livestock operations (origin) and agricultural census block groups (destinations) respectively. The second objective was to identify areas that were prone to nutrient transport as determined from the model results based on environmental conditions related to floodplain and length of streams dataset using the Getis-Ord GI* statistic. Finally, using the objective function of the transportation problem, the transportation costs associated with hauling manure from the source to the destinations were calculated.

What Have We Learned?

The distribution of manure showed an unbalanced transportation problem such that available farmland that could receive manure exceeded the supply of the livestock operations. The findings suggest there is adequate agricultural land for manure distribution in the watershed. Additionally, areas indicating clustering in the distribution of manure were further examined to determine the potential for nutrient transport off the land and into nearby water bodies based on the environmental conditions used. Approximately 98% of receiving agricultural census block groups fell in the EC-1 classification, which indicates a very low potential for environmental conditions to influence nutrient movement off farmland receiving manure from the 31 CAFFs studied. Approximately 2% and 1% of total acres receiving manure had a moderate to high potential for flooding respectively and were found in Upper Maumee and St. Joseph sub-basins. The identified sub-basins are recommended target areas for best management practices in reducing nutrient runoff. In using the Getis-Ord GI* statistic in ArcMap, Auglaize, Upper Maumee, Lower Maumee, and Cedar-Portage sub-basins were identified as critical areas of concern with high total acres showing high clustering of stream length.

Future Plans

The transportation problem is a type of linear programming problem where goods and services are transported from one set of sources to one set of destination points to minimize transportation costs. There are two phases to the transportation problem – finding the initial basic feasible solution while the second phase involves optimizing the initial basic feasible solution. This study focused on finding the initial basic feasible solution for manure distribution and application in the Maumee River Watershed. Future research could include optimization of the initial basic feasible solution per the transportation problem process to test the robustness of the results from the first phase.

Secondly, the transportation model coded for this dissertation was based on the manure supply of permitted livestock facilities engaged in only swine and dairy production. The model could be refined to include the supply of all livestock operations in the watershed in addition to all destination agricultural lands. With transportation costs being a major overhead cost for producers, the model can also be calibrated based on minimal travel time as an economic utility for producers and farmers.

Furthermore, given the costs involved in the construction of manure storage facilities and the regulations surrounding manure application as identified in Ohio State Bill 1, locations for ‘manure- sheds’ can be identified for manure storage during off seasons for application. A GIS optimal model can be developed to determine the minimum cost and distance efficient for the location of the proposed ‘manure-sheds’ where both small and medium facilities with limited storage facilities can transport their manure to a centralized location for storage, while also serving as the point of distribution and utilization for farmers.

Authors

Dr. Patrick L. Lawrence, University of Toledo

Corresponding author email address

Patrick.lawrence@utoledo.edu

Additional author

Dr. Edwina Teye, University of Toledo

Acknowledgements

Ohio Sea Grant

Ohio Department of Higher Education

Ohio Pork Council

Ohio Livestock Association

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Pull-Plug Sedimentation Basin for Dairy Manure Management

Purpose

Many small and mid-sized dairy farms use flush systems for manure removal due to reduced chore time and increased barn cleanliness. Often, flush systems require greater attention to onsite water management and frequent lagoon maintenance. While anaerobic lagoons provide some digestion of manure solids and sludge storage, solids removal may help increase lagoon capacity and reduce costly lagoon sludge removal. A pull-plug sedimentation basin (PPSB) is a passive solids removal system that can reduce the operational time and cost of the overall manure management system by acting as both a sedimentation basin and pre-lagoon solids filter system.

Larger, denser particles accumulate on the basin floor, while buoyant particles (e.g., undigested fiber, waste forage, bedding, etc.) form a floating mat on the surface. The mat acts as a natural filter and retains some of the solids from the waste stream. The PPSB was developed as part of a collaborative effort between USDA NRCS and small dairy producers in Missouri. This abstract provides background and basic information on the PPSB, while more performance evaluation of the system based on nutrient retention, costs, and maintenance and operational considerations can be found in a University of Missouri Extension publication Eq302 (Canter et al., 2021).

What Did We Do?

Design details of a working PPSB were documented, and performance evaluation was conducted based on grab samples of the flush and PPSB locations. Critical design considerations for the PPSB including design, hydraulic loading, location of the pull-plug location, and construction details were reported in the Extension publication (Canter et al., 2021). The concrete entry ramp into the PPSB should have a maximum slope of 12:1 (or 5 degrees) (Figure 1) to minimize wheel slippage and potential for equipment overturns. The example provided in Figure 1 is of a typical PPSB design that serves a herd of ~150 milking cows with a single-flush volume of ~7,000 gallons but also represents the smallest recommended size of the system. A minimum depth of 6 feet is needed to keep settling solids out of the discharge stream.

Figure 1. Profile and plan views of typical PPSB (dimensions in feet).

Detailed discussion of the advantages and disadvantages of the PPSB system was reported in the Extension publication. Relatively little maintenance has been reported, while the pull-plug is the only moving part and may need to be replaced if damaged during cleaning or degradation, Figures 2 and 3. Details such as the management and sampling and analysis were discussed, and a case study was conducted to document the information of a PPSB system of a 120-hd dairy farm in Missouri, with a flush system and sand lane, as well as a performance evaluation.

Figure 2. A PPSB system in operation at a dairy farm.
Figure 3. PPSB with liquid discharge pipe, after manure solid was removed.

What Have We Learned?

The owners are satisfied with the performance of the PPSB, which is considered a low-maintenance, low-technology option to efficiently manage manure solids within a flush system. The primary benefit of the PPSB is a reduction in time spent agitating and removing solids/sludge in the lagoon. When less capacity in the lagoon is used for solids treatment and storage, there is more room to store water and longer intervals between repairing or unclogging pumps and the water system. There are typically three to four clean-out periods per year, depending on PPSB and herd sizes and other factors.

The primary benefit of the PPSB is the removal of manure solids using a low maintenance system, resulting in longer intervals between lagoon agitation and land applications. Approximately 23,450 cubic feet of manure solids were prevented from entering the lagoon each year, along with 6,454 pounds of nitrogen (438 pounds as ammonia-nitrogen) and 2,415 pounds of phosphorous. These represent 13 percent and 28 percent of manure-based nitrogen and phosphorous, respectively, being retained in the PPSB.

Future Plans

Additional sampling just before or during clean-out is necessary for a more accurate performance determination. PPSB installed at larger dairy farms, and those using different bedding should be evaluated for performance and documented the cost savings as compared with other popular solid separation systems.

Authors

Teng Lim, Extension Professor, Agricultural Systems Technology, University of Missouri

Corresponding author email address

Limt@missouri.edu

Additional authors

Timothy Canter, Extension Specialist, Agricultural Systems Technology, University of Missouri

Troy Chockley, Environmental Engineer, Natural Resource Conservation Service, United States Department of Agriculture

Additional Information

Canter, T., T.-T. Lim, and T. Chockley. 2021. Considerations of pull-plug sedimentation basin for dairy manure management. University of Missouri Extension. https://extension.missouri.edu/eq302

Acknowledgements

USDA NIFA, Water for Food Production Systems Program A9101, for supporting the project. It is titled “Management of Nutrients for Reuse”, a multi-faceted project that involves professionals from the University of Arkansas, University of Nebraska, Colorado School of Mines and Metallurgy, Case Western University, and University of Missouri.

Joseph Zulovich, Agricultural Systems Technology, University of Missouri

Richard Stowell, Biological Systems Engineering, University of Nebraska

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Opportunities and Challenges for Dairy Manureshed Across the US

Purpose

The “manureshed” refers to the land base needed to assimilate the nutrients produced by a livestock operation without presenting a danger to water, land, and air resources. Trends toward large dairies in many regions of the US, often with high density of livestock relative to the amount of land available for nutrient application, have increased in recent decades. Consequently, import of feed and forage often leads to nutrient surpluses and the need to transport manure off farm for land application. Our purpose was to evaluate the status of dairy manuresheds across the US to highlight challenges and opportunities to improve nutrient balances and facilitate manure nutrient redistribution when needed.

What Did We Do

Our group produced case-studies of manureshed management from four major dairy producing states across the US. We reviewed the predominate structure of dairies in those states and analyzed the primary challenges that must be addressed to safely assimilate nutrients. We focus on reviewing the extent of off-farm redistribution of manure that is needed in each of those states, limitations to redistribution, and approaches that can be built upon to facilitate redistribution. In the Minnesota case-study, where nutrient management data is publicly available for Confined Feeding Operations, GIS software was used to estimate manure transport distances for varying cropping systems and dairy cattle breeds. For Idaho, New Mexico, and Pennsylvania, whole-farm modelling is referenced to understand nitrogen (N) and phosphorous (P) balances on a range of dairies.

What Have We Learned

Soil P assimilation capacity was the predominate factor constraining manureshed land requirements in three of the four states studies. However, nitrate leaching potential was the largest constraint in New Mexico, where dairy forages were largely grown on irrigated lands near rivers. GIS analysis in Minnesota estimated that an average travel distance of 4.1 km for manure transport was required for dairy with 1000 or more cows. The Minnesota case-study also revealed smaller manuresheds were required, per unit of energy-corrected milk, for Jersey cattle compared to the larger Holsteins. Modelled nutrient budgets for Idaho indicated a greater need for off-farm transport, suggesting that expanded application of dairy manures on alternative crops (such as potatoes, sugar beets, and barley) should be considered. In New Mexico, large dairies and limited cropland has caused extensive import of feed from other states and Mexico, with informal nutrient brokering networks developing. In Pennsylvania, dairy producing counties are largely overall sinks for nutrients, but historic heavy manure applications on fields near dairy barns often necessitates greater redistribution of manure nutrients within individual dairies or transfer to local crop farms.

Multiple approaches for improving nutrient balances and distribution of manure were identified in the case studies. Continuing advances in dairy nutrition and cattle genetics are helping to improve nutrient balances and reduce quantities of N and P excreted. When nutrient surpluses necessitate off-farm transport, informal networks for connecting dairies with surplus nutrients with crop farms that have nutrient assimilation capacity, described in New Mexico, provide a basis for development of similar networks elsewhere. Manure processing developments also provide possibilities for more economical transport or reuse of manure nutrients from farms with liquid handling.

Future Plans

The current work provides an overview of the current status of manureshed management in dairy regions. Continuing work is needed to refine nutrient balances for individual farms and to continue to develop tools that assist farmers in understanding nutrient balances and manureshed requirements on their farms. Involvement of social scientists and economists is needed to further develop networks for manure redistribution. Our work also points to the need for greater federal and state cost sharing and more technical support from government, universities, and farm organizations to facilitate more intensive evaluation of manureshed requirements and transport of manure when needed.

Authors

Curtis Dell, Soil Scientist, USDA-ARS, Pasture Systems and Watershed Management Research Unit, University Park, PA
Curtis.Dell@usda.gov

Additional Authors

    • John Baker, USDA-ARS, St. Paul, MN
    • Sheri Spiegal, USDA-ARS, Las Cruces, NM
    • Sarah Porter, Environmental Working Group, Minneapolis, MN
    • April Leytem, USDA-ARS, Kimberly, ID
    • Colton Flynn, USDA-ARS, Temple, TX
    • Alan Rotz, USDA-ARS, University Park, PA
    • David Bjornberg, USDA-ARS, Kimberly, ID
    • Ray Bryant, University Park, PA
    • Robert Hagevoort, New Mexico State Univ., Clovis, NM
    • Jeb Williamson, New Mexico State Univ., Las Cruces, NM
    • Amalia Slaughter, USDA-ARS, Las Cruces, NM
    • Peter Kleinman, USDA-ARS, Fort Collins, CO

Additional Information

C.J. Dell et al., 2022. Challenges and opportunities for manure management across US Dairy systems: Case Studies from four regions. Journal of Environmental Quality. (In press in pending special edition on manureshed management).

Acknowledgements

USDA Agricultural Research Service and the Dairy Agroecosystems Workgroup (DAWG, USDA-ARS)

 

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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