Dr. Richard J. Hull, Dr. Noel Jackson, Haibo Liu, G.R.A., Normand E. Allaire, S.A., UNIVERSITY OF RHODE ISLAND, PLANT SCIENCES DEPARTMENT, Kingston, Rhode Island, U.S. Department of the Interior, Water Resources Scientific Information Center 
Geological Survey, 1989-1991
AVERAGE SOIL WATER NITRATE-N CONCENTRATION from May 1990 to September 1990 & from October 1990 to April 1991.