||Accounting Method for Tracking Relative Changes in Agricultural Phosphorus Loading to the Tar-Pamlico River.
Johnson, A. M.;
Osmond, D. L.
||North Carolina State Univ., Raleigh. Dept. of Soil Science.; North Carolina Dept. of Environment and Natural Resources, Raleigh. Div. of Water Quality.; North Carolina Dept. of Environmental and Natural Resources, Raleigh. Aquifer Protection Section.
Hyde County(North Carolina);
Basin Oversight Committee (BOC)
||Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy.
||The Tar-Pamlico Agricultural Rule requires the development of a methodology that accounts for phosphorus losses and gains from agricultural activities in the basin. The Rule recognizes potential challenges associated with this objective, and calls for the Basin Oversight Committee (BOC) to form a phosphorus technical advisory committee (PTAC) to evaluate this issue and provide recommendations to the BOC. The following report compiles the findings of the PTAC and conveys its recommendations to the BOC. Foremost, the PTAC has determined that a quantitative accounting of watershed or county-scale agricultural phosphorus loading is not achievable due to the complexity of phosphorus behavior and transport within a watershed, the lack of suitable data required to adequately quantify the various mechanisms of phosphorus loss and retention within watersheds of the basin, and the problem with not being able to capture agricultural conditions as they existed in 1991. In addition, modeling phosphorus loss under agricultural conditions is highly inaccurate. The PTAC has instead evaluated, to the limits of available data, trends in land use and management related to agricultural activity in the basin from 1991 to the present. In addition, it has developed recommendations for qualitatively tracking relative changes in practices that either increase or decrease the risk of phosphorus loss from agricultural lands in the basin on an annual basis. The committee believes this approach to be the best alternative toward meeting the spirit of the Rule. Overall, the acreage of cropland in the basin (#1 in the table below) has decreased, although only slightly. The number of livestock and poultry (2) experienced an increase between 1991 and 2003, although the greatest increase occurred in the mid-1990s, after which populations declined. This change in livestock distribution and numbers increased total phosphorus excreted by 10%. There is no accurate means to calculate fertilizer phosphorus inputs into the basin for the baseline or any subsequent years. Nor is it possible to retroactively establish fertilizer P management changes that may have occurred across the basin since 1991. Thus, while excreted phosphorus inputs to the basin increased, cropland acres decreased, and the effect of these factors on total P inputs or losses is uncertain. Looking forward, the addition of a new 4.75 million bird layer facility in Hyde County would add approximately 2 million pounds
|PUB Date Free Form
||Oct 21 2005
||98B | Agricultural Economics; 57H | Ecology; 57Y | Toxicology; 72B | Algebra, Analysis, Geometry, & Mathematical Logic; 48G | Hydrology & Limnology; 48B | Natural Resource Management; 98C | Agricultural Equipment, Facilities, & Operations
||PC | AC