PHOSPHORUS IN RUNOFF FROM TWO WATERSHEDS IN LOST RIVER BASIN, WEST VIRGINIA

Abstract

The loss of nutrients in runoff from soils treated with heavy manure application is a major cause of poor surface water quality in the United States. Poultry production in the Hardy County, West Virginia, has increased considerably since the early 1990s. The Lost River basin contains the highest density of poultry houses in the county. Most of phosphorus (P)-rich manure produced is land applied, and concerns over water quality impacts are widespread. The objectives of this study were to apply the Natural Resources Conservation Service technique on two watersheds (Cullers Run and Upper Cove Run) in the Lost River basin to predict the loss of water and P from soils by runoff and to estimate the impact on water quality. The predicted average runoffwas 4374 m 3 /ha per year, and agreed with the observed average runoff of 4267 m 3 /ha per year. This gives an annual runoff of 74.6 million m 3 for the two watersheds. The average P loss by runoffwas 0.57, 1.98, and 5.51 kg/ha per year from soils under forest, pasture, and crop, respectively. The high P loss by runoff was probably associated with application of P fertilizer or poultry manure to cropped soils. The total annual loss of P from soils by runoff was estimated at 16,435 kg. The predicted P concentration varied widely in runoff water generated from different soils and land covers. The average P concentration in runoff water was 133, 432, and 1146 μg/L for forestland, pastureland, and cropland, respectively. The predicted average P concentration in runoff was 224 μg/L for the two watersheds. However, the observed P concentration was very low (1.3-13.3 μg/L) in the monthly water samples (January-December 2006) collected from the Lost River, where the pH ranged between 7.6 and 8.4. The average pH in soils was 4.22, 5.42, and 6.15 for forest-land, pastureland, and cropland, respectively. Changing the pH of runoff water from acidic (soils) to the alkaline range in the Lost River could precipitate calcium phosphates and decrease P concentration in water. The technique predicted P concentration in runoff at the edge of field. The increase in water pH as well as P removal by aquatic weeds and algae could be the cause of the low P concentration observed in the Lost River.