17.3 Emissions Summaries
Table 17.10 below shows the comparison of animal population and national NH3 emissions total between NEI 2020 and 2023 NEI EPA estimates. The average national ammonia emissions changes (tons/year) between 2020 and 2023 NEI EPA estimates range from -15% (Dairy), -5% (Beef Cattle), +6% (Swine), +8% (Layer) to +18% (Broiler). These changes in emissions result from a combination of differences in meteorology, animal counts, and some updated manure management practice information.
| Animal Type | NEI Year | Animal Population (Number of animals*1000) | Total Emissions (tons/year) |
|---|---|---|---|
| Beef | NEI2020 | 80,658 | 698,170 |
| Dairy | NEI2020 | 18,802 | 580,858 |
| Swine | NEI2020 | 77,255 | 845,306 |
| Layer | NEI2020 | 509,914 | 127,548 |
| Broiler | NEI2020 | 1,676,730 | 299,691 |
| Beef | NEI2023 | 76,851 | 662,348 |
| Dairy | NEI2023 | 18,380 | 491,368 |
| Swine | NEI2023 | 74,820 | 898,378 |
| Layer | NEI2023 | 522,578 | 138,323 |
| Broiler | NEI2023 | 1,664,545 | 354,398 |
2023 NEI EPA estimates results are shown as total NH3 emissions by county in Figure 17.2. The hotspots are seen to be in the San Joaquin Valley in CA, parts of the Midwest and eastern NC. Beef and dairy cattle emissions drive the hotspots in California mostly. Poultry emissions dominate the southeastern US hotspots, and swine emissions are very prevalent in NC. Turkeys (which are not estimated outside of the FEM model) are important in both NC and in MN areas of the country.
In general, there is very little change (< 0.01 % decrease) in ammonia emissions from 2020 to 2023 NEI EPA estimates as the increases and decreases in emissions from different animal types balance out which is the result of the increases or decreases by different animal types across the states.
Figure 17.2: Total EPA estimated NH3 emissions from the 2023 livestock waste sector.
17.3.1 Improvements/Changes in the 2023 NEI
From the 2020 to 2023 NEI, the only change in methodology was the use of farm management practice survey information for a selection of states. More details are provided below.
17.3.1.1 Farm Manure Management Practices Information Improvements
For the 2023 NEI, a survey was conducted to collect information on farm and manure management practices in the following 7 states and animal types:
- North Carolina: beef/dairy/swine/broilers/layers
- Oklahoma: beef/dairy/swine/broilers/layers
- Minnesota: beef/dairy/swine/broilers/layers
- Nebraska: beef/dairy/swine/broilers/layers
- California: dairy only
- Missouri: beef/dairy/swine/broilers/layers
- Texas: beef/dairy/swine/broilers/layers
This survey has several sub-sections based on animal type, including housing type, manure storage, manure cleanout and handling, manure land application, animal management (if applicable), and other information. The responses from the survey questions provided input data to the farm probabilities input files and FEM configuration. The information on the 7 survey states was used in 2023 NEI for the 7 states accordingly. For the rest of the states, FEM configuration was kept at default values which means the same values as the 2020 NEI, which was based on the NAHMS.