"New/February1991/10M.""Water Quality.""Focus area : a quality world : bringing about change.""Published by University Extension. University of Missouri-Columbia.""This publication was written by Karen DeFelice, former associate extension agronomist; Nyle Wollenhaupt, former state extension agronomist; and Daryl Buchholz, state extension agronomist. This material is based upon work supported by the United States Department of Agriculture, Extension Service, under special project number 89-EWQI-1-9203.