An assessment is made of sources of variation in pesticide analyses for soil cores taken during the period May 1973 through September 1974 from two watersheds. A number of relationships to methodology, chemical species, topography, soil conditions, and weather are identified. Criteria are given for assessing down-slope movement within and between sampling segments and movement within the profile. A detailed description is given of weather and watershed conditions associated with wintertime runoff events on the larger watershed and with major spring and summer events on both watersheds in 1975. Emphasis is placed on characterizing boundary conditions at the beginning of each event in relation to weather sequences that preceded it. Only portions of the pesticide data set, stored at the Environmental Research Laboratory, Athens, GA, were used in these evaluations. However, important features of soil, topography, management and weather are identified in relation to useful variation in the data. The described relationships should be helpful in interpreting and modelling data from these watersheds for both pesticides and nutrients.

Includes bibliographical references (page 76). Grant no. R-800483.