He had a really good sense of humour and was always telling "little jokes".
"Everyone kind of remembers him as a big friendly giant because he was so tall."
Mcdonald has set up a Givealittle page for the family to help raise money to help the family through the grieving process and to cover funeral costs.
"Everyone is absolutely devastated. Very lost. It's crazy how freak accidents can just happen."
On the Givealittle page, Mcdonald said the family was going through a really hard time after Johnstone died in a tragic farm accident.
"Not only has it left a massive whole in her heart, her three children have lost a great father. Please help her and the kids out with a donation to help them get through this awful time."
Johnston is from the Mackenzie region and leaves behind three brothers.
Worksafe has been notified and the death referred to the coroner, according to earlier police reports.