Dr. Sherman Ellsworth Johnson, 81, a government agricultural economist for more than 30 years before retiring in 1965, died of a heart ailment Friday at his home in Strasburg, Va.

Dr. Johnson first came to Washington in 1933 as a researcher for the Brookings Institution, then became a regional director of the Land Purchase program in Lincoln, Neb., from 1934 to 1936.

He returned to Washington and joined the Bureau of Agricultural Economics in the Agriculture Department.He remained with Agriculture until his retirement.

During World War II, he served as chief of production programs at the War Food Administration, helping to set farm production goals.

In 1959 he became an agricultural consultant to the government of India. Dr. Johnson continued to visit and advise the Indian government through the early 1970s.

Dr. Johnson was author of a number of technical articles on agricultural development. He also published an autobiography, "From St. Croix to The Potomac - Reflections of a Bureaucrat."

He was a former president of the American Farm Economic Association and of the International Conference of Agricultural Economists from 1959 to 1961.

Dr. Johnson received a number of government awards, including the Distinguished Federal Civilian Service Medal.

Born of a dairy farm in Scandia, Minn., he earned bachelor's and master's degrees at the University of Minnesota, and a doctorate in agricultural economics at Harvard University.

He is survived by his wife, Evelyn, of the home; two daughters, Lenore E. Cowan, of New York City, and katherine A. Nelson, of New Haven, Conn.; a son, Paul R. Johnson, of Raleigh, N.C.; and five grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the University of Minnesota's School of Agriculture's Alumni Foundation, St. Paul, Minn., 55105.