Glossary
- AEU (animal equivalent unit): One AEU equals 1000 pounds of animal weight. As an example, a calf that weighs 500 pounds is 0.5 AEUs.
- Animals sold: the number of animals sold in a year by all farms in a state or county, as reported by the U.S. Census of Agriculture.
- Biosolids: nutrient-containing byproduct of wastewater treatment, also known as sludge.
- Crop nitrogen: nitrogen that is calculated to be removed from cropland by crops harvested in a state, county, region, or watershed. These calculations are based on standard crop nitrogen removal factors and crop harvests reported in the U.S. Census of Agriculture.
- Crop phosphorus: phosphorus that is calculated to be removed from cropland by crops harvested in a state, county region or watershed. These calculations are based on standard crop phosphorus removal factors and crop harvests reported in the U.S. Census of Agriculture.
- Cropland: land from which crops were actually harvested. This does not include land on which planted crops failed, idle cropland, pasture, woodland or other farmland.
- Excess nutrients: Lakes and streams naturally contain some nitrogen and phosphorus, but excess nutrients can cause undesirable algae growth, which degrades water quality. Phosphorus concentrations in unpolluted lakes and streams are typically less than 0.025 parts per million, while lakes and streams with phosphorus concentrations greater than 0.05 parts per million are generally considered to be polluted (Leinweber et al., 2002). Water with a concentration greater than 10 parts per million of nitrate (a nitogen-oxygen compound) does not meet drinking water standards for public water systems (EPA, 2002).
- Fertilizer nitrogen: commercial fertilizer nitrogen available for crop application in a state, county, region or watershed.
- Fertilizer phosphorus: phosphorus that is reported or estimated to be added to cropland in fertilizer applications in a state, county, region or watershed.
- Groundwater: water beneath the earth's surface that supplies wells and springs.
- Harvested crops: The annual yields for crops harvested in a state or county as reported by the U.S. Census of Agriculture. Only crops that occupied at least 1% of a state's harvested cropland acreage were included in each state's nutrient budget (list of crops included in the budgets).
- Inventory: The total number of animals on all farms in a state or county at the end of the year, as reported by the U.S. Census of Agriculture.
- Manure nitrogen: nitrogen estimated to be recoverable from the manure produced by livestock and poultry within a county, state, region or watershed. Estimates are based on standard manure production factors and livestock/poultry numbers reported in the U.S. Census of Agriculture.
- Manure phosphorus: phosphorus that is calculated to be recoverable from the manure produced by the animals in a state, county, region or watershed. Calculations are based on standard manure production factors and animal populations reported in the U.S. Census of Agriculture.
- Nitrogen: a nutrient that is used by plants and animals to form proteins. Excess nitrogen in estuaries (such as the Chesapeake Bay) can cause undesirable algae growth which degrades water quality for aquatic life. Excess nitrogen in groundwater can degrade the quality of the resource for drinking water.
- Nutrient: an element required by plants and animals in order to complete their life cycles. The three nutrients that plants require in the greatest quantities are nitrogen, phosphorus and potassium. Excess nutrients can degrade water quality.
- Nutrient balance: the difference between nutrient inputs and outputs. When the nutrient balance is close to zero, nutrients applied in manure and fertilizer are closely matched to crop utilization. When the nutrient balance is positive, nutrient inputs exceed outputs. When the nutrient balance is negative, nutrient outputs exceed inputs.
- Nutrient budget: a summary of the major nutrient inputs and outputs to the cropland in a geographic region.
- Nutrient flows: the nutrient inputs and outputs for cropland in a geographic region. Currently the only flows considered in these budgets are nutrients in manure and fertilizer applied to cropland and nutrients removed from cropland in harvested crops.
- Nutrient inputs: nutrients in materials that are applied to cropland (primarily fertilizer and manure).
- Nutrient outputs: nutrients in materials that are removed from cropland (primarily harvested crops).
- Nutrient stock: nutrients stored in the soil of the cropland in a geographic region. Over time, a positive nutrient balance increases the nutrient stock and a negative nutrient balance decreases the nutrient stock.
- Phosphate: a compound of phosphorus and oxygen. Fertilizer labels typically indicate phosphate content rather than phosphorus content. One pound of phosphate contains 0.437 pounds of phosphorus.
- Phosphorus: a nutrient that is used by plants for energy storage and transfer. Excess phosphorus in lakes and streams can cause undesirable algae growth which can degrade water quality for aquatic life.
- Phosphorus excreted: the amount of phosphorus produced per animal per day in animal manure. Not all of the phosphorus excreted by animals is recoverable.
- Physiographic province: An area of land with similar terrain, rock types, geologic structure and history. The United States is divided into eight physiographic divisions, 25 physiographic provinces and 86 physiographic sections. The boundaries and names of these regions are provided on the U.S. Geologic Survey's Physiographic Regions page.
- Production period: the number of days per year that an animal would typically spend on a farm.
- Recoverable manure nutrients: nitrogen or phosphorus in manure that is assumed to be usable for cropland application or other distribution. Manure from animals that are not kept in confinement is not considered to be recoverable. Even when animals are kept in confinement, some nitrogen and phosphorus is lost in the process of manure storage and handling. The recoverable manure fractions used in these budgets are based on averages for the U.S. given by Van Dyne and Gilbertson (1978).
- Runoff: Rain and snow melt that does not enter the soil, but instead travels over the soil surface to lakes and streams.
- Watershed: an area of land from which the surface runoff drains to a specific tributary, stream, river or estuary. A watershed contains many subwatersheds that drain to a common location. For example, the Chesapeake Bay watershed has many subwatersheds that drain to streams and rivers, which all eventually drain to the Chesapeake Bay.
