Sources, Instream Transport, and Trends of Nitrogen, Phosphorus, and Sediment in the Lower Tennessee River Basin, 1980-96

Wastewater discharge.

Annual mean flow rate and (where available) effluent concentration data from wastewater dischargers.

Multiply annual mean flow rate by reported effluent concentration, or (for nitrogen) by empirically adjusted effluent ammonia concentration, or by typical concentration of nitrogen and phosphorus for discharge categories.

Typical concentration for municipal wastewater:
nitrogen - 15 mg/L,
phosphorus - 3.5 mg/L, for industrial wastewater, estimates from National Oceanic and Atmospheric Administration (1993).

Atmospheric deposition.

Precipitation chemistry data from the NADP/NTN network.

Weight NADP/NTN nitrate and ammonia wet deposition rates to each basin; multiply weighted nitrate wet deposition rate for each basin by regional coefficient to calculate nitrate dry deposition rate; combine wet and dry deposition rates to arrive at total nitrogen deposition rate; no deposition rate calculated for phosphorus.

Regional dry nitrate coefficients;
Tennessee: 0.7826
Alabama: 0.8571
Kentucky: 0.8333.

Fertilizer application--sales.

County estimates of commercial sales of nitrogen and phosphorus fertilizers.

No calculations

No coefficients

Fertilizer application--
recommended rates.

County estimates of harvested acreage, by crop type.

Multiply harvested acreage by recommended fertilizer application rates for medium-soil test results.

Recommended fertilizer application rates, varying by crop:
nitrogen--rates range from

0 (soybeans) to

200 (tobacco) lb/acre
phosphorus--rates range from

20 (soybeans) to

90 (tobacco) lb/acre.

Nitrogen fixation.

County estimates of harvested acreage of soybeans.

Multiply harvested acreage of soybean crop by nitrogen fixation rate.

Nitrogen-fixation rate for soybeans: 105 lb/acre.

Crop uptake.

County estimates of harvested amount, by crop type.

Multiply harvested amount by coefficients of nitrogen and phosphorus uptake rates, expressed as pounds per acre of nutrient removed per harvested amount per acre; simplify to pounds per harvested amount.

Nitrogen and phosphorus uptake rates, varying by crop;
nitrogen--rates range from

1.75 (corn) to

5.15 (soybeans) lb/bushel
phosphorus--rates range from

0.22 (corn) to

0.46 (soybeans) lb/bushel.

Livestock waste.

County estimates of nitrogen and phosphorus in livestock waste, by livestock class.

Sum estimates for each livestock class.