Malcolm L. Merriam, 70, a former economist with the Department of Commerce who later owned a farm on Sugar Loaf Mountain near Stronghold, Md., died at the Potomac Valley Nursing Home Sunday following a stroke.

Mr. Merriam was born in Berkeley, Calif., and came to Washington when his father, the late Dr. John C. Merriam, was appointed president of the Carnegie Institute here. He graduated from Central High School and later earned bachelor's and master's degrees in economics from Yale University.

Mr. Merriam worked briefly in California and then returned to Washington and became an associate of the Brookings Institute. He joined the Commerce Department in 1939. One of his chief interest was commercial credit. He made a study of it and helped found the department's credit analysis unit and became its chief.

He served in the Coast Guard in World War II in Greenland and the Pacific. He returned to Commerce and remained here until 1949, when he resigned and bought a farm on Sugar Loaf Mountain. He raised cattle there and became an amateur naturalist while still maintaining a residence in Washington. He had lived here since selling the farm in 1962.

Mr. Merriam was married to Anita Wells Merriam, an economist in the Treasury Department, who died in 1970.

Survivors include a brother, Lawrence, of Berkeley, Calif.