Data and Methodology

Data provided on the map represents estimates of locations and statistics in an attempt to accurately document poultry feeding operations and their impact on the landscape. EWG and Waterkeeper Alliance assume no responsibility for locational accuracy, errors or omissions represented on the maps.

Poultry Operation Map Attributes

County: Name of the North Carolina county in which animal feeding operation exists.

Estimated birds per person in the county: Estimated number of birds at the county level divided by 2010 U.S. Census county population data. (See Methods below for more detail.)

Estimated hogs per person in the county: Allowable number of hogs per county from the North Carolina DEQ, as of January 2018, divided by 2010 U.S. Census data.

Number of new poultry operations since 2008: Poultry operation locations that were not present on 2008 National Agriculture Imagery Program photography, but were visible in subsequent imagery, aggregated at the county level. (See Methods below for more detail).

Number of new birds since 2008: Estimated bird counts associated with all operations detected after 2008 and aggregated at the county level. (See Methods below for more detail.)

Year detected: Imagery year the operation was first detected (2008, 2012, 2016 or 2018; see Methods below for more detail).

Poultry or swine operations within three miles: Number of swine or poultry operations within a three-mile radius of the poultry location point.

Poultry operation within 500-year floodplain: Locations within the FEMA 500-year flood hazard map are marked “Yes.”

Number of poultry barns: Number of poultry barns visible at the location as calculated by EWG and the Waterkeeper Alliance, under contract with Justin S. Quinlivan.

Estimated number of birds: Estimated number of birds derived from barn counts and data from the USDA Ag Census. (See Methods below for more detail.)

Estimated annual manure output: Estimated yearly output of waste generated by individual facilities derived from barn counts and data from the USDA Ag Census and the North Carolina Agricultural Chemicals Manual. (See Methods below for more detail.)

Methods

Poultry Locations

This dataset was created by surveying satellite imagery of North Carolina from 2018 (Sentinel-2 10m). Poultry operations were identified by distinctive clusters of long, metal barns with attached feed canisters. For each identified operation, we recorded a location and a count of barns.

Identified operations were checked for accuracy using 3m-resolution satellite imagery of North Carolina from 2018 (Planet). Locations were not included if they appeared to be abandoned, for instance, locations where barns did not have feed canisters, had dilapidated roofs or were overgrown.

Operations were dated by comparing them to previous years of imagery and recording the earliest year in which the operation is visible. Previous imagery was from the 2016, 2012, and 2008 National Agriculture Imagery Program, so the establishment of these operations can be dated only approximately to one of these years.

Animal Counts

To estimate poultry animal counts, an average square footage per bird was used and then allotted to each barn, assuming a constant barn size for all poultry facilities in North Carolina. To identify a constant barn size, the 25 counties in the state with the most poultry facilities were identified, and one random facility was selected within each of those counties. Barn-building footprints were digitized for each selected facility, resulting in a total of 104 barns. The distribution of square footage for these 104 barns was normally distributed as shown below, with a mean barn size of 24,430 square feet. This value was assumed to be the size of every poultry barn in North Carolina.

Figure 1. Distribution of barn size from building footprints

The square footage allotted to each bird will vary based on poultry production system –  pullets, turkeys, broilers or layers. Square footage per production system was derived from industry standards and is listed in Table 1 along with the source. Broilers and pullets were combined, as a credible source for pullet square footage could not be found. In addition, pullets make up a very small proportion of total birds in North Carolina, according to the 2012 Ag Census. 

As the type of production system cannot be determined from aerial photography, nor does permit data exist for poultry facilities in North Carolina, the 2012 Ag Census was used to estimate the percentage of each poultry production system within each county. This by-county distribution was then applied to each facility within that county to allot bird populations, assuming a constant 24,430 square feet per barn.

Poultry Distribution

Although the distribution of production system varied by county, broilers were by far the most common across the state. The state distribution of production system was 83 percent broilers, 9 percent turkeys, 5 percent laying hens and 3 percent pullets (USDA Ag Census, 2012).

Recommended Square Footage Per Animal

 

Industry Guidelines

Source

Broiler and Pullets

0.8

National Chicken Council

Layer

0.465

United Egg Producers

Turkeys

3.0

USDA NIFA

Table 1. Guidelines on square footage allotment by poultry production system.

Manure Estimate

The North Carolina Agricultural Chemicals Manual (NCACM, 2016) was used to calculate manure amounts for both poultry and swine. Methods used to derive total manure, nitrogen and phosphorus values for each animal system are described below.

Swine Manure Methods

The NCACM lists manure and nutrient values for the various swine production systems, including Farrow-To-Wean, Farrow-To-Feeder, Farrow-To-Finish, Wean-To-Feeder, Wean-To-Finish, and Feeder-To-Finish. Permit data for swine includes the production system for each swine facility, with Feeder-To-Finish comprising more than half of all facilities in the state, followed by Wean-To-Feeder and Farrow-To-Wean (Table 2). Allowable animal counts and production system from permit data were used to assign manure and nutrient values to each facility, using values listed in Table 3. In cases where permit data included production systems not included in the NCACM (Gilts, Boar/Stud, and Other), values for Farrow-To-Feeder were used. Manure and nutrient values were found for both anaerobic lagoon liquid and anaerobic lagoon sludge, then summed to get total manure, nitrogen and P205 values in tons/year for each facility. P205 was multiplied by 0.44 to convert to elemental phosphorus, according to guidance provided by the Midwest Planning Service Livestock Waste Facilities Handbook (MWPS-18).

Swine Production System

Number of Facilities

Swine – Feeder to Finish

1281

Swine – Wean to Feeder

493

Swine – Farrow to Wean

331

Swine – Wean to Finish

56

Swine – Farrow to Feeder

41

Swine – Farrow to Finish

30

Swine – Gilts

27

Swine – Boar/Stud

13

Swine – Other

6

Table 2. Statewide distribution of swine production facilities in North Carolina from permit data.

Manure Volume and Weights in Typical North Carolina Animal Production Systems

Animal Production System

Accumulated Manure (Gallons/Animal/Year)

Anaerobic Lagoon Liquid – Swine

 

Farrow-To-Wean (per sow)

3,203

Farrow-To-Feeder (per sow)

3,861

Farrow-To-Finish (per sow)

10,478

Wean-To-Feeder (per pig)

191

Wean-To-Finish (per pig)

776

Feeder-To-Finish (per pig)

927

Anaerobic Lagoon Sludge – Swine

 

Farrow-To-Wean (per sow)

433

Farrow-To-Feeder (per sow)

522

Farrow-To-Finish (per sow)

1,417

Wean-To-Feeder (per pig)

30

Wean-To-Finish (per pig)

26.3

Feeder-To-Finish (per pig)

135

Table 3a. Swine manure production values for lagoon sludge and lagoon liquid (from NCACM).

Total Nitrogen (N) and Phosphorus (P as P2O5) from Manure Sources

Animal Production System

N

P2O5

 

Pounds of Total Nutrients Per 1,000 Gallons

Anaerobic Lagoon Liquid – Swine

 

 

Farrow-To-Wean (per sow)

2.4

.9

Farrow-To-Feeder (per sow)

3.6

1.4

Farrow-To-Finish (per sow)

3.6

1.4

Wean-To-Feeder (per pig)

3.6

1.4

Wean-To-Finish (per pig)

3.6

1.4

Feeder-To-Finish (per pig)

3.6

1.4

Anaerobic Lagoon Sludge –  Swine

20.4

30.6

Source: 2018 North Carolina Agricultural Chemicals Manual, specifically Chapter IV—Fertilizer Use, page 64, “Livestock and Poultry Manure Production Rates and Nutrient Content.” 

** In cases where permit data included production systems not included in the NCACM (Gilts, Boar/Stud, and Other), values for Farrow-To-Feeder were used.

Table 3b. Swine nutrient values for lagoon sludge and lagoon liquid (from NCACM).

Poultry Manure Methods

In lieu of permit data for poultry facilities in North Carolina, the 2012 Ag Census was used to determine the distribution of poultry production systems within each county. This distribution was then assumed for all mapped poultry facilities in that county. This same by-county distribution from the 2012 Ag Census was used to determine animal counts for each facility, as described previously. The four production systems for poultry included in the 2012 Ag Census and their associated production system from the NCACM are shown in Table 4. Estimated animal counts and the production system were used to assign manure and nutrient values to each poultry facility using values from Table 5. Total manure, nitrogen and P205 values in tons/year were calculated for each facility. P205 was multiplied by 0.44 to convert to elemental phosphorus, according to guidance provided by the Midwest Planning Service Livestock Waste Facilities Handbook (MWPS-18).

Ag Census Production Systems

NCACM

Production Systems

Broiler

Broiler – Whole House

Pullets

Broiler Pullets

Layers

Layers

Turkeys

Turkey Hen

Table 4. 2012 Ag Census production system and associated NCACM production system

Manure Volume and Weights in Typical North Carolina Animal Production Systems

Animal Production System

Tons / 1,000 Bird Capacity/Year

Poultry Litter – Broilers

7.2

Poultry Litter – Broiler Pullets

7.2

Poultry Litter –  Layers

24

Poultry Litter –  Turkeys

25

Table 5. Poultry manure production values (from NCACM)

Total Nitrogen (N) and Phosphorus (P as P2O5) from Manure Sources

Animal Production System

N

P2O5

 

Pounds of nutrient per ton

Poultry Litter – Broilers

57.8

40.0

Poultry Litter – Broiler Pullets

57.8

40.0

Poultry Litter –  Layers

47.6

44.7

Poultry Litter – Turkeys

54.0

48.2

Source: 2018 North Carolina Agricultural Chemicals Manual, specifically Chapter IV-Fertilizer Use, page 64, “Livestock and Poultry Manure Production Rates and Nutrient Content.” 

Table 5b. Poultry nutrient values (from NCACM)

References

NCACM, 2018 North Carolina Agricultural Chemicals Manual, College of Agriculture and Life Sciences, North Carolina State University, Dec. 1, 2017.

MWPS-18, Livestock Waste Facilities Handbook. 1993. Midwest Plan Service (MWPS): Ames, Iowa.

US Department of Agriculture, National Agriculture Imagery Program. Aerial Photography 2008, 2012, 2016 and 2018. Available at https://www.fsa.usda.gov/programs-and-services/aerial-photography/imagery-programs/naip-imagery/. Accessed January 1, 2019. USDA-Aerial Photography Field Office, Salt Lake City, UT.

European Space Agency. (2019). Sentinel 2. Paris, France. https://sentinel.esa.int/web/sentinel/sentinel-data-access

Planet Team (2019). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://api.planet.com.