A small agricultural watershed on Cowarts loamy sand in the Georgia Coastal Plains was planted in corn (Zea mays L.) each year from 1969 to 1971. Surface and subsurface water samples were collected during each natural rainfall runoff event and NO3‐N was determined.The initial weighted average NO3‐N concentration was 5 ppm in the subsurface runoff for 3 months before the first planting. The average was 7 ppm in 1969, 10 ppm in 1970, and 9 ppm in 1971. The concentration of NO3‐N in most of the surface runoff for 3 years was less than 1 ppm; the maximum was 3 ppm. Subsurface flow accounted for 80% of the total runoff during the study period. Thus, greater amounts of NO3‐N were discharged in subsurface flow than in surface flow from this watershed.