A Health & Safety Executive (HSE) investigation was carried out on the farm after a worker's arm was broken in two places when he was dragged into a net-cleaning machine, a court in North Somerset heard.
The 32-year-old was using the specialist washing machine for the first time to clean the nets used to cover the mushroom beds at the farm.
The nets were fed through the machine to be washed but the clamping mechanism that held them in place as they went in was ineffective.
The HSE investigation discovered safety devices were deliberately removed to allow workers to hold the nets in place by hand. In addition, the worker had received no training to use the machine.
Inspector's conclusion Safety first
Health & Safety Executive inspector Christine Haberfield, speaking after sentencing, said: "By disabling the safety mechanisms and allowing workers to feed it by hand, the farm not only failed the worker but all the other workers who used the machine and who could also have easily been injured.
"It is vital that safety devices are used and checked to make sure they work properly all the time and that anyone operating them is trained so that they know how to use them safely."