Effect of Manure Application On Nitrogen Contamination for Watersheds in West Virginia.

Poultry production in Hardy County, West Virginia has increased considerably since the early 1990s. The Lost River basin contains the highest density of poultry facilities in the county. Most of the N-rich poultry litter produced is land applied, and concerns over water quality are widespread. The objective was to apply the NRCS exploratory technique on two watersheds (Cullurs Run and Upper Cove Run) in the Lost River basin to estimate the loss of nitrate-N from soils by runoff and leaching and to predict the impact on water quality. The predicted annual nitrate-N loss by runoff was 192 Mg while that by leaching was 764 Mg, and their combined amount represented the annual loading for the Lost River. The predicted average nitrate-N concentration in runoff and leaching water was 2.57 and 45.1 mg/L, respectively. These data would give an estimated average nitrate-N concentration of 10.4 mg/L in the Lost River. The observed nitrate-N concentration in 12 monthly samples collected from the Lost River ranged from 2.41 to 19.9 mg/L with an average of 7.11 mg/L (s.d.= 4.68). The relatively low nitrate-N concentrations observed in the river could be attributed to assimilation by algae, weeds, and aquatic plants as well as denitrification in stream water under anaerobic conditions. When factors affecting N concentration in streams are considered, the technique could estimate the impact on water quality. We concluded that the exploratory technique could provide quick estimation and identify hot spots for large areas of agricultural land. Thus, lengthy and site-specific studies could be focused on certain areas of high risk.