Estimated Animal Agriculture Nitrogen and Phosphorus from Manure

Photo of chickens, cattle and sheep

About this indicator
Animal agriculture manure is a primary source of nitrogen and phosphorus to surface and groundwater. Manure runoff from cropland and pastures or discharging animal feeding operations and concentrated animal feeding operations (CAFOs) often reaches surface and groundwater systems through surface runoff or infiltration. Permitting discharging CAFOs to limit nitrogen and phosphorus discharge to surface waters, and implementing best management practices outlined in a manure management plan are critical steps to protecting water quality. This indicator shows animal agriculture manure produced in states in 2007 (the year of the last Census of Agriculture) and expressed in terms of nitrogen and phosphorus content, rather than total amounts of manure, since different animal types produce manure with differing nitrogen and phosphorus concentrations. Data are for cattle, swine, poultry (chickens and turkeys), sheep, and horses. Data are presented as 1000s of kg of manure nitrogen and phosphorus as well as kilograms of manure nitrogen and phosphorus per km2 of farmland.

Estimated nitrogen (N) and phosphorus (P) produced from animal manure in 2007.

State Estimated animal manure
(1000 kg of N)
Estimated animal manure
(1000 kg of P)
Estimated animal manure per farm land area (kg of N/km2) Estimated animal manure per farm land area (kg of P/km2)
Alabama 133,956 41,438 3,678 1,138
Alaska 796 225 221 62
Arizona 50,998 12,309 483 117
Arkansas 179,024 56,005 3,183 996
California 327,287 75,388 3,184 733
Colorado 136,460 38,852 1,074 306
Connecticut 3,493 749 2,105 451
Delaware 20,080 5,994 9,729 2,880
Florida 101,939 30,901 2,709 821
Georgia 158,802 48,575 3,810 1,165
Hawaii 7,957 2,485 1,756 548
Idaho 115,094 27,493 2,473 591
Illinois 105,906 36,690 976 338
Indiana 103,411 35,432 1,727 592
Iowa 398,551 144,981 3,198 1,163
Kansas 293,838 84,863 1,568 453
Kentucky 144,122 43,414 2,544 766
Louisiana 59,630 18,259 1,819 557
Maine 6,109 1,391 1,118 255
Maryland 37,297 10,548 4,474 1,265
Massachusetts 3,672 818 1,745 389
Michigan 75,204 19,574 1,858 484
Minnesota 211,302 68,684 1,941 631
Mississippi 112,038 34,567 2,517 777
Missouri 261,450 84,045 2,228 716
Montana 131,048 41,155 532 167
Nebraska 314,619 96,219 1,705 521
Nevada 22,792 6,765 955 283
New Hampshire 2,676 581 1,407 305
New Jersey 4,394 1,114 1,487 377
New Mexico 80,695 20,699 462 118
New York 85,755 17,913 2,943 615
North Carolina 215,818 80,115 6,201 2,302
North Dakota 88,069 27,324 550 171
Ohio 108,025 32,516 1,907 574
Oklahoma 283,852 87,463 1,998 616
Oregon 74,777 21,237 1,127 320
Pennsylvania 125,555 32,946 3,978 1,044
Rhode Island 495 120 1,747 424
South Carolina 47,205 15,054 2,381 759
South Dakota 189,425 59,013 1,071 334
Tennessee 124,787 38,148 2,803 857
Texas 699,431 206,361 1,325 391
Utah 56,209 17,083 1,251 380
Vermont 15,934 3,047 3,201 612
Virginia 102,834 30,895 3,137 943
Washington 63,537 16,069 1,054 266
West Virginia 27,580 8,304 1,842 555
Wisconsin 191,761 42,098 3,117 684
Wyoming 69,123 21,070 566 172

Sources: The number of animals per state are from USDA’s 2007 Census. Estimated manure N and P contents are from Ruddy et al. 2006. 2007 farm land acreage is from USDA's National Agricultural Statistics Service: Farm Numbers, Farms and Land in Farms, Final Estimates, 2003-2007.

Download the manuredata.xlsx(2 pp, 44 K)

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Sources of data
1. U.S. Department of Agriculture. 2009. 2007 Census of agriculture: United States summary and state data. Vol 1. AC-07-A-51.

2.  Ruddy, B.C., D.L. Lorenz, and D.K. Mueller. 2006. County-level estimates of nutrient inputs to the land surface of the conterminous United States, 1982–2001: U.S. Geological Survey Scientific Investigations Report 2006-5012.

3.  U.S. Department of Agriculture. National Agricultural Statistics Service, Farms and Land in Farms, Final Estimates, 2003–2007. See also the Table 825 of the U.S. Census Bureau’s 2012 Statistical Abstract, Agriculture: Farms and Farmland.

Data source information
Data were collected for the following animal types: cattle (milk cows, beef cows, steers, heifers, slaughtered cattle), hogs and pigs, chicken (broilers, layers, and pullets), turkeys, sheep, lambs, horses, and ponies. The numbers of animals were collected from the 2007 U.S. Department of Agriculture (USDA) Census, except for steers, heifers, and on-farm cattle slaughter, as the USDA Census no longer reports on these cattle categories. Inventory for these animals were estimated per Ruddy et al. 2006. Manure nitrogen and phosphorus production rates (kg/animal/day) for each animal type are also from Ruddy et al. 2006. Farm land acreage is from the National Agricultural Statistics Service. The current definition of a farm, first used for the 1974 census, is any place from which $1,000 or more of agricultural products were produced and sold, or normally would have been sold, during the census year. Acreage designated as ‘‘land in farms’’ consists primarily of agricultural land used for crops, pasture, or grazing. Acres were converted to km2 for this indicator in order to be consistent with other indicators.

What to consider when using these data

  • The rate of delivery of nitrogen and phosphorus from land-applied fertilizer such as manure to streams is dependent on the amount, timing, and placement of application, as well as best management practices to minimize runoff from fields.
  • In cases where certain states did not report total numbers of hogs and pigs or poultry to the 2007 USDA Census, the total number of head was estimated based on reported number of head for counties that reported by head, plus an estimate of the number of head for counties that reported by farm size, by using the median value in the ranges reported for each farm size.
  • The 2007 USDA Census does not differentiate between tom and hen turkeys. Therefore, the averages of the manure nitrogen/phosphorus production rates (kg/animal/day) for tom and hen turkeys provided by Ruddy et al. 2006 were used as estimates of the manure nitrogen/phosphorus production rates for all turkeys.
  • Based on a review of the literature, USDA sites, and university extension programs, weaning age is variable with reported average values of 120-220 days (cattle are considered calves until weaning). Heifers not used for breeding are typically slaughtered at 9-10 months. Therefore, it was assumed (consistent with Ruddy et al. 2006) that 50% of the cattle, excluding cows, were slaughtered within their first year of life and that the average lifespan was 170 days.
  • All other cattle, excluding cows and slaughtered cattle, were assumed heifers or steers in equal proportions, based on Ruddy et al. 2006 procedures.

References and links to other data sources
1. U.S. Department of Agriculture.  Manure management webpage.

2. U.S. EPA. State animal feeding operations program status reports.

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