V. WEBSTER JOHNSON, 86, a former official of the Agriculture Department and the Agency for International Development, died of congestive heart failure July 10 at a hospital in DeKalb, Ill. He had been in DeKalb to attend the funeral of a sister.

Dr. Johnson, a former resident of Washington and College Park, joined the Agriculture Department's bureau of agricultural economics in 1935. He was head of the division of land economics in 1954 when he left the department to join the Mutual Security Administration, a predecessor of AID.

Later he worked two years for the Ford Foundation, and in 1958 returned to the foreign assistance field as a specialist in land use and agricultural credit. He joined AID when it was created in 1961 and his work there took him frequently to Iran and Korea. He retired in 1970 but remained as a consultant for two years before moving to Southern Pines, N.C.

A native of DeKalb, Dr. Johnson was a graduate of Northern Illinois University. He received a doctorate in agricultural economics from the University of Wisconsin, and taught at the University of Maryland for four years before joining the Department of Agriculture.

Dr. Johnson wrote several books and articles on land uses, policies and problems.

His wife, Josephine, died in 1984. Survivors include one son, V. Webster Johnson Jr. of Rockville; one daughter, Jacqueline Gaensslen of Madison, Conn., and three grandsons.