A spokeswoman for St John Ambulance said when the initial call came in, they were told it was an electrocution.
"We deployed several resources but when staff arrived on the scene, the patient was deceased," she said.
Mr Johanson's friends spoke of his huge involvement in the community, in particular sport.
George Crosse, who lives in Dannevirke but still owns a farm at Weber, said Mr Johanson was well known in the district and would be sorely missed.
"The Weber community is a very tight-knit community. I knew him for many years and he was a great man, easygoing and popular with other residents. He was involved in the rugby club and horse sports and took great interest in what was happening in the district."
Mr Crosse said Mr Johanson grew up on the farm which was owned by his maternal grandparents and after leaving schooltrained as a teacher.
"He taught at Dannevirke High School before returning to run the farm."