After high school Johnson got his private and commercial pilot's certificates and airframe and power plant ratings at the University of Illinois Institute of Aviation.
In the 1980s Johnson served three two-year terms in the Iowa House of Representatives,[1] helping to author, manage, and secure passage of a number of bills supporting soil and water conservation and energy efficiency.
In 1993 President Clinton appointed Johnson Chief of the Soil Conservation Service (SCS), the largest (by "covered" acreage) of the US Department of Agriculture's 29 agencies, where he served under Secretaries Mike Espy and Dan Glickman.
While there, he passionately advocated for public policies to elevate conservation efforts on privately owned “working” land, including cropland, pasture, and rangeland.
[11] After his retirement, Johnson lived on his northeast-Iowa family dairy, sheep, and Christmas tree farm Oneota Slopes and wrote essays for the Iowa progressive news site Bleeding Heartland.
After his death, Johnson's former colleagues and family launched an effort to extend his legacy—aiming, eventually, toward the US federal government's adoption of a national private lands conservation act/policy.