Wellman was an agricultural economics specialist in the College of Agriculture
cooperative extension service from 1925 until 1934. In 1929, he became an associate in the
Giannini Foundation of Agricultural Economics. He returned to Berkeley in 1935 after serving a year in
Washington, D.C., as chief of the General Crops Section of the United States
Agricultural Adjustment Administration. He was an associate professor of agricultural economics in the College of Agriculture and an associate agricultural economist in the Agriculture Experiment Station. He became a full professor in 1939 and was appointed director of the Giannini Foundation in 1942. He served as a director of the
Federal Reserve Bank of San Francisco from 1943 to 1954. Wellman became the first vice president of the University of California in 1958 after serving since 1952 as vice president-agricultural sciences. He served as acting president of the University in 1967. . ==Legacy and honors==