Lee Waters fell from the tipper truck because Mole Valley Feed Solutions had failed to put basic safety measures in place to ensure the large cover could be taken off safely.
Chippenham Magistrates Court heard on 29 May that Waters delivered grain on a tipper truck to customers.
He was removing the cover from his vehicle’s load at the Mole Valley’s feed mill at the Porte Marsh industrial estate in Calne on 8 July 2011 when he fell from the steps of his lorry.
He suffered a fractured pelvis and wrist and was hospitalised for seven days. He was unable to leave his house unassisted and was off work for 11 weeks while he recovered.
Since the incident he has been told he will regain only 80% of the use of his wrist and has been diagnosed with arthritis.
The incident was investigated by the Health and Safety Executive (HSE), who brought the prosecution.
Mole Valley Feed Solutions pleaded guilty to breaching Regulation 6(2) of the Work at Height Regulations 2005 and was fined £6,000 and ordered to pay £4,087 in costs.
After the hearing HSE Inspector Ian Whittles said: "Mole Valley Feed Solutions failed to ensure Mr Waters’ safety while he was unloading on their site. As a result he has been caused a great deal of pain and suffering.
"Simple measures could have been taken such as providing a long-handled crank handle to operate the sheet from the ground. This arrangement is commonly provided in lorries for such purposes.
"It is vital that employers provide the right equipment for their staff to do their job safely when working at height."