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Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania : characterization of surface-runoff and ground-water quantity and quality in a small carbonate basin near Churchtown, Pennsylvania, prior to terracing and implementation of nutrient management : water-quality study of the Conestoga River headwaters, Pennsylvania

Water-Resources Investigations Report 93-4119

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Abstract

Surface-runoff and ground-water quantity and quality of a 22.1-acre field site were characterized from January 1983 through September 1984, before implementation of terracing and nutrient-management practices. The site, underlain by carbonate rock, was cropland used primarily for the production of corn and alfalfa. Average annual application of nutrients to the 14.4 acres of cornfields was 410 pounds of nitrogen and 110 pounds of phosphorus. About three times more nutrients were applied during the 1984 water year than during the 1983 water year. During the investigation, 714,000 cubic feet of runoff transported 244 tons of suspended sediment, 300 pounds of nitrogen, and 170 pounds of phosphorus during the 1984 water year. Runoff from storms on frozen ground produced the highest loads of nitrogen. Regression analyses indicate that runoff rates and quantities were controlled by precipitation intensities of quantities and the amount of crop cover, and that mean concentrations of nitrogen for runoff events increased with increased surface-nitrogen applications made prior to runoff. Ground-water levels responded quickly to recharge, with peaks occurring several hours to a day after precipitation. Median concentrations of dissolved nitrate in ground water ranged from 9.2 to 13 milligrams per liter as nitrogen. A lag time of 1 to 3 months was observed between the time that nitrogen was applied to the land surface and local maximums in nitrate concentrations were detected in ground water unaffected by recharge events. About 3 million cubic feet of ground water and an associated 2,200 pounds of nitrate-nitrogen discharged from the site during the study period. For the study period, 42 percent of the precipitation recharged to ground water, 10 percent became runoff, and 48 percent evapotranspired. Inputs of nitrogen to the study area were estimated to be 93 percent from manure, 5 percent from commercial fertilizer, and 2 percent from precipitation. Nitrogen outputs from the system were estimated to be 38 percent to crop uptake, 39 percent to volatilization, 20 percent to ground- water discharge, and 3 percent to surface runoff.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania : characterization of surface-runoff and ground-water quantity and quality in a small carbonate basin near Churchtown, Pennsylvania, prior to terracing and implementation of nutrient management : water-quality study of the Conestoga River headwaters, Pennsylvania
Series title:
Water-Resources Investigations Report
Series number:
93-4119
Edition:
-
Year Published:
1996
Language:
ENGLISH
Publisher:
U.S. Geological Survey : Earth Science Information Center, Open-File Reports Section [distributor],
Description:
ix, 103 p. :ill., maps ;28 cm.