Ammonia Loss and Emission Reporting: Considerations for Cattle Operations

By Rick Stowell, UNL Associate Professor and Extension Specialist, Animal Environment


A resource reality of cattle production is that only 10-30% of the nitrogen (N) that is consumed (i.e. fed protein) is utilized by animals for growth, reproduction, milk production, and maintenance needs. Unused N is excreted, primarily in urine. Nitrogen is an essential, valuable plant nutrient, so recycling of N is highly desirable and occurs when urine and feces are applied directly onto soil in a pasture, range or other grazing scenario, or collected manure is applied to cropland. In each situation, however, there will be opportunities for N to be lost to the environment, with potential implications for water and air quality. While livestock production is not the only source of N, producers should recognize that agriculture is clearly the dominant contributor of N to the environment on regional and national scales, and animal manure is a key source along with commercial fertilizer.

Loss of N to the atmosphere is a relatively new environmental concern to livestock operations. In contrast, N losses to groundwater (via leaching through the soil profile) and surface waters (via runoff into lakes and streams) are known to impair water quality, which is evidenced by the presence of well-head protection areas, regulation of manure management on confined animal feeding operations, and other water quality protections being put in place. Less attention has been given to N loss through air emissions – primarily as ammonia (NH3) and to a much lesser extent nitrous oxide (N2O). More than a dozen studies have looked into ammonia-N loss from Great Plains beef cattle feedyards, with losses ranging seasonally from 30 to 70% as a percentage of fed nitrogen. This helps explain why N fertilizer levels in feedlot manure are relatively low.

Emissions of ammonia have generally not been a major focus of regulation in the U.S. Given that nitrogen is the main component (~78% by volume) of air, some may question why the concern at all. Atmospheric ammonia levels typically observed in farming areas have not been shown to have direct human health impacts. Research has supported some indirect environmental and health challenges, though; some of which have led to regulation of ammonia emissions in specific regions like Western Europe. In the atmosphere, N exists as non-reactive N2 gas, which is not directly usable by plants. Addition of ammonia to air contributes ‘reactive N’ to the environment. When ammonia reacts with other airborne compounds, potentially problematic particulates or ‘secondary compounds’ can form. Ammonia-based particulates can deposit in downwind water bodies or sensitive areas that could become over-fertilized and experience ecosystem changes. ‘Fine particulates’ that form from reactions of atmospheric ammonia with industrial emissions (e.g. NOx and SOx) have been shown to reduce visibility and have respiratory impacts.

Ammonia is not classified as a ‘criteria pollutant’ under the Clean Air Act. Particulate matter however, is a listed criteria pollutant, subject to Clean Air Act regulation – including requiring air permits and potential mitigation practices – and fine particulates (PM2.5) are of special concern. In certain regions of the U.S., such as the San Joaquin Valley in CA, problematic PM2.5 levels exist and regulatory actions have been implemented. Environmental groups looking for broader regulation of animal agriculture have initiated efforts to have ammonia declared a criteria pollutant, subject to Clean Air Act regulation. In early 2018, EPA denied a request to regulate ammonia emissions from animal feeding operations under the Clean Air Act, but further requests may be expected.

Environmental groups have had some success in federal courts securing decisions that direct EPA to enforce two federal reporting requirements for air emissions (ammonia and possibly hydrogen sulfide) from livestock and poultry operations. The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the Emergency Planning and Community Right-to-Know Act (EPCRA) were enacted later than and are separate from the Clean Air Act. CERCLA’s purpose is to minimize environmental risks from spills and chemical supplies, while EPCRA was created primarily to help communities plan for chemical emergencies. These reporting regulations were originally developed to address pollutant releases from industrial sources, not air emissions from routine agricultural operations. However, this distinction is not clearly stated in the acts, leading to differing interpretations. In 2008, an EPA ruling exempted animal feeding operations from having to report routine air emissions under CERCLA and all but ‘Large CAFO’ from reporting under EPCRA. In April of 2017, the DC Circuit Court of Appeals ruled that EPA did not have authority to enact these exemptions. EPA requested a 90-day delay on receiving a court mandate, which was to occur on January 22, 2018, enforcing its ruling and opening livestock and poultry operations to consideration under CERCLA/EPCRA. As of January 31, 2018, there has been no official word on the requested delay, nor has a court mandate been received by EPA, leaving the effective enforcement date on day-to-day status.

The April 2017 decision by the DC Circuit Court of Appeals made a clear statement about EPA’s [lack of] authority to exempt animal feeding operations from reporting routine air emissions under CERCLA and EPCRA. The court’s decision, however, also created considerable uncertainty for livestock and poultry producers, and the scrambling efforts by EPA to offer guidance, while helpful, have not removed much of the uncertainty. This has been especially true for beef cattle producers, who are trying to determine what types and sizes of operations need to report, how to estimate emissions, and how to go about meeting reporting obligations.

These screening questions provide initial herd-size trim points for reporting of air emissions by beef cattle operations. If other livestock are also raised on what would be considered the same facility or site, then reporting needs to be based upon the combined emissions.

1. Is the cattle herd (feeders and cows / cow-calf pairs) being raised on the site continuously below 200 head?
If “Yes”, it is doubtful that this operation emits reportable quantities of ammonia based upon current approaches for estimating ammonia emissions. Stay informed, but do not report routine air emissions.

2. Is the operation grazing-based such that fewer than 200 head of cattle are confined in lots or buildings for periods of time where manure needs to be collected and stored?
If “Yes”, it is doubtful that this operation emits reportable quantities of ammonia. Stay informed, but do not report routine air emissions.

Grazing cattle apply urine and feces directly to land for use by vegetation, which constitutes natural application of manure nutrients. EPA guidance ( states that emissions from fertilizer application (including manure) may be excluded from the estimation of emissions for reporting purposes. Note that there is no EPA exemption for grazing operations; only the exclusion of emissions from land receiving manure as fertilizer.

The following two cases – neither of which is now exempt from reporting – illustrate this screening:

This ranch raises cows, their calves, and a few bulls on range and meadow pasture year-round, except for brief periods when groups of animals are brought in to a central handling area (for treatment, receiving new cattle, holding calves for sale, etc.). Emissions from the range and pasture may be excluded for reporting purposes as applied fertilizer / manure nutrients, but not emissions from the central handling area. Given a handling area that can accommodate a maximum of 150 head at any one time, it is doubtful that ammonia emissions exceed 100 lb. per day. If more than 200 head were held, but the animals are always kept in pens for such a brief period that manure does not collect to the point of needing to be handled and stored, it is also doubtful that ammonia emissions exceed 100 lb. per day. Reporting is not necessary.

This farm grazes cows, their calves, and a few bulls on corn residue and cover crops from October through April, and confines and feeds them in comparatively small ‘sacrifice lots’ through the growing season when there is no access to pasture for grazing. Given that the sacrifice lots do not sustain growth of vegetation to utilize applied nutrients, they end up functioning like an open lot, not like pasture or other land-application areas. Ammonia emissions from this area may need to be considered for reporting purposes and, at more than 200 head, might exceed 100 lb. per day. Use of one or more estimating tools is advised to get estimates and inform your decision. {Note that similar logic would be applied to an operation that grazes pasture during the growing season and confines cattle during the winter months. The main difference would be that estimated emissions should be lower during cold conditions than during hot weather.}

3. Is the operation considered a Large CAFO based upon cattle numbers and are cattle confined during some or all of the growing season (spring – fall)? If “Yes”, it is likely that this operation emits reportable quantities of ammonia. When cattle numbers exceed 1,000 animal units and the operation collects and stores manure during warm conditions, current approaches for estimating emissions generally produce estimates that exceed 100 lb. per day for open lots and common confinement buildings (i.e. slatted-floor or bedded barns). Continue reading for other considerations and guidance.

If none of these scenarios fit the operation – the response to each of the three questions was “No” – then it is not cut and dry as to whether the ammonia emitted from the operation is likely to stay below or exceed the reporting threshold of 100 lb. per day. Continue reading for other considerations and guidance.

For the thousands of livestock and poultry producers who might be affected by these reporting requirements, a key question is “Did the 2017 circuit court of appeals decision resolve the issue or just form the next step in regulatory wrangling?” Some commodity associations and producers believe that the issue is decided. Others believe that legislative or other federal action will be implemented that will exclude animal feeding operations from needing to report routine air emissions or restrict EPA enforcement of these regulations within animal agriculture. Even if federal action is taken, there may be a period of time during the interim when enforcement actions could occur, so producers are encouraged to assess risks and seek additional guidance on reporting estimated ammonia emissions.

The following are provided only as points of discussion.

Leading toward reporting:
• An operation places being in compliance with all applicable regulations and/or minimizing risk of being out of compliance (and open to fines) as a top priority.
• An operation is or has been in a controversial situation or under scrutiny by an activist group, disgruntled neighbor, etc. or under environmental/legal pressure where a complaint to EPA is an anticipated recourse for the other party.
• Advice from commodity association / other trusted parties is to report.

Leading toward holding off / not reporting:
• An operation is confident that EPA enforcement will be restricted or very passive [that EPA action will match its general position that air emissions from routine operations on animal feeding operations do not warrant an emergency response].
• An operation’s perception is that risks of reporting exceed those of not reporting.
• Advice from commodity association / other trusted parties is to hold off / not report.

The following information and guidance are provided to assist cattle operations in reporting air emissions or documenting why reporting is not needed on the basis of estimated emissions.

Different approaches exist for estimating ammonia emissions and satisfy the ‘good faith estimate’ requirement for CERCLA and EPCRA. Conservative ammonia emission factors – in this case, numbers representing emissions on a per-head basis – may be useful to get a ballpark emissions estimate or to quickly determine numbers for use in reporting. The factors in Table 1 ( are based upon results from in-depth emissions-monitoring studies conducted at a very limited number of finishing facilities located in the Great Plains.

For each facility type, multiply the Upper-bound and Lower-bound factors by the number of head in the facility to get daily Upper-bound and Lower-bound emissions, respectively, for the facility; then add up numbers in columns to obtain total facility emissions for the operation. Reporting requirement is based upon comparison of Upper-bound emissions (shaded box) vs. 100 lb. per day reportable quantity for ammonia.

For example, estimated peak daily ammonia emissions for a 2,500-head (Large CAFO) feedlot that has capacity for 2,000 head in open lots and 500 head in a recently added beef building are shown in Table 2 ( These emissions estimates were calculated quickly using the given factors and represent comparatively conservative estimates for reporting purposes. Current approaches generally estimate peak daily ammonia emissions from Large-CAFO beef facilities to be in excess of 100 lb. per day [during summer conditions]. Since other approaches would likely produce a smaller, but still-reportable estimate, there may be little incentive for this operation to do additional work just to generate and report a somewhat smaller number. But the operation could certainly choose to do so. A 250-head feedlot, however, would likely compare this quick estimate against the 100-pound-per-day reporting threshold and see value to trying another approach, since the additional effort might enable the operation to document no need to report air emissions.

Producers may want to consider other estimation methods. Some may be looking for a less-conservative estimate that is below the reporting threshold, in which case they could document a choice to not report. Others may want estimates that more accurately represent the facilities and conditions on their operations. Each of the following approaches, like the emissions factors presented above, has its own set of strengths and weaknesses.

One different approach for estimating ammonia emissions involves estimating manure N loss from excretion through storage and assuming that all N is lost as ammonia. The Ammonia Emissions Estimator ( worksheet provides book-value N production and loss numbers for several types of housing and manure storage facilities, along with guidance on coming up with high- and low-end daily emission rates for use in reporting. An operation that maintains thorough feed and manure nutrient records may be able to generate its own ammonia emissions estimate using similar concepts, though it’s hard to see the effort involved being worthwhile for most operations.

A main advantage of this approach is that the data set is more robust with manure nutrient data representing many more operations and types of facilities than have been part of emissions studies. There is also some flexibility allowed in selecting conditions and values within given ranges that match those of the operation.

Emission monitoring studies provide direct measurement information, which is desirable for accurately estimating daily emissions and assessing what factors influence emissions. Unfortunately, very few monitoring studies have been conducted on U.S. cattle operations. Monitoring air emissions from beef production facilities is challenging for several reasons, including substantial expense. Emissions monitoring on Southern High Plains Cattle Feedyards ( may offer specific information for use with open-lot operations. Beef barn air quality research ( conducted on South Dakota and Iowa facilities offers information on emissions from modern bedded facilities. Research conducted in the Netherlands and other Western European countries may offer more detailed information for slatted-floor barns and other types of housing facilities.

CERCLA and EPCRA both require the same emissions estimates (Upper-bound and Lower-bound daily emissions).

CERCLA reporting goes to EPA and involves making an initial call (email option now available), submitting a written report within 30 days of the initial call, and following-up with a report one year later. Step-by-step Reporting requirements ( and links to forms are provided by EPA.

EPCRA reporting goes to state and local emergency contacts and involves making an initial call and submitting a written report within 30 days of the initial call. Guidance for submitting an EPCRA report in Nebraska ( was developed previously (2008) and – other than needing updated contact info – is still useful.

Questions about EPCRA reporting persist, as EPA “interprets the statute to exclude farms that use substances in ‘routine agricultural operations’ from reporting under EPCRA section 304.” EPA’s 2008 ruling, though, had required EPCRA reporting [by Large CAFO] and its current position is subject to further rulemaking. Risks of reporting and not reporting under EPCRA are similar to those for CERCLA, so one could assume that operations that submit a CERCLA report would submit an EPCRA report also, but it is not at all clear that this is required.

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