Nitrate‐Nitrogen and Phosphorus Contents of Streams Draining Small Agricultural Watersheds in Kentucky

Eight streams draining agricultural watersheds in the important physiographic regions of Kentucky were sampled monthly from January through May in both 1971 and 1972. The objective of the study was to determine the effects of land use and geology on the concentrations of nitrate‐N and P in the stream water. The land use ranged from almost completely forested to mostly cultivated. There was not a good relationship between nitrate‐N and land use. Nitrate‐N varied from 6 ppm to zero, with the highest value being found in a stream draining a watershed which was 98% in bluegrass pasture. The P concentrations in the stream water were closely related to local geology and not to land use. A comparison between the 1921 data of McHargue and Peter and 1971–72 data from the same geological areas showed very little change in mean nitrate‐N or P concentrations.