Animal waste levels on Scorecard are estimated by combining animal population data for states, counties, or livestock operations with information about animal waste factors. Waste factors represent the quantities of different kinds of waste produced by different types of animals and are determined on a per animal basis. All factors are from the North Carolina Agricultural Chemicals Manual. More on the assumptions involved with using the animal waste factors to calculate Scorecard's animal waste data.
WASTE FACTORS FOR SCORECARD'S ANIMAL WASTE CATEGORIES
Animal Weight: Animal weight levels represent an average weight for each animal type and are taken from the North Carolina Agricultural Chemical Manual. For livestock operation calculations (available for North Carolina only) animal weight was used to estimate the total amount of animal waste per operation.
Animal Waste: For each animal type, waste is expressed as tons/yr of feces and urine.
Amount of waste per year = animal population x animal waste factor (tons of waste/animal-yr)
Volume of Waste: Volume of waste is estimated by multiplying the rate of feces/urine
production by a conversion factor (tons/yr to gal/yr) and dividing by the density of the waste
Volume of waste per year = [[feces (tons/yr) x 2000 lbs/ton] / [waste density (lbs/ft^3)]] x [7.48 gal/ft^3] x [animal population]
Nitrogen: A nitrogen factor, represented in pounds of nitrogen per ton of waste generated, has been determined for a variety of animals. Multiplying the total yearly animal waste by the nitrogen factor results in an estimate of the amount of nitrogen contained in the animal waste on a yearly basis.
Total Nitrogen per year = total animal waste generated (tons/yr) x nitrogen factor (lbs N/ton of waste) x animal population
Nitrogen lost to the Atmosphere All animal waste contains nitrogen, which can occur in a number of different compounds. For every pound of waste produced, a certain amount of nitrogen escapes to the air, or volatilizes. These rates of loss to the atmosphere have been experimentally determined for different animal types. The total amount of nitrogen lost to the atmosphere is calculated by multiplying the rate of loss (lbs N/ton of animal waste) by the total amount of animal waste produced (tons/yr)
Nitrogen lost to atm per year = (lbs N lost to atm/ton waste produced) x (tons waste/yr)
Phosphorus Yearly levels of phosphorus contained in animal waste are estimated by multiplying the total yearly animal waste by the phosphorus factor.
Total Phosphorus per year = total animal waste generated (tons/yr) x phosphorus factor (lbs P/ton of waste) x animal population
HOW CAN I GET A LIST OF SCORECARD'S ANIMAL WASTE FACTORS?
Animal waste factors for the types of livestock Scorecard covers (cattle, hogs, poultry and sheep) are available from the North Carolina Agricultural Chemicals Manual. The waste factors are available as a pdf file from Chapter 10 of the manual by clicking on "Livestock Manure Production Rates and Nutrient Content." This file contains the values of the factors used to generate waste, volume, nitrogen, and phosphorus levels for each livestock type.