Adrian Pickett had been contracted by retired farmer James Headland, 73, to carry out the work at his farm. Pickett did so using his own tractor-mounted rotary flail hedge cutter, Lincoln Magistrates' Court was told.
The accident happened on 13 February 2013. Headland later died of his injuries.
An investigation by the Health and Safety Executive (HSE) found the contractor had failed to properly maintain his machinery and fit it with the correct guarding.
Pickett pleaded guilty to breaching s 3(2) of the Health and Safety at Work Act. He was sentenced to 80 hours of community service and ordered to pay almost £6,560 in costs.
An information sheet published by the HSE, Safe use of rotary flail hedge cutters, lists "being hit by material or other debris ejected by the cutters" as one risk of injury associated with the machinery.
The document goes on to advise operators "check all guards and other protective devices are in place before starting work. Don't use the machine if the guards are missing or damaged."
