Harvesting and grading operations within the GB potato industry has seen 2 fatalities and 4 serious injuries in the past 5 years. You have a legal duty of care to your staff in preparation for your harvest.
AHDB Potatoes http://potatoes.ahdb.org.uk/safe-potato-operations has training modules available.
These modules are designed for training groups of employees in safe harvesting and grading practices. At the end of the module you can test understanding and print a certificate of training for each participant. The certificate should be retained as proof of your training.
The training focusses on the safe operation of grading and harvesting machinery with emphasis on the safe stop procedure. This is in addition to the need for care in the set-up of machines to avoid damage, in particular the bruising of potatoes. Good Health & Safety makes good business sense.