The NFU is reminding farmers of their legal obligation to keep mud off the road when transporting sugar beet.
“Wet weather means there is an increased risk of high levels of mud getting on to the roads,” said an NFU spokesman.
“As well as being illegal, this is a problem which has led to serious accidents in the past and it is essential that members take steps to minimise its impact.”
Farmers and vehicle operators who deposit mud on the road are potentially liable for a range of offences.
While there is a range of powers available to the police and highways department, the primary powers fall under the Highways Act 1980.
Civil action may also be a possibility where the mud contributes to a personal injury, property damage, or any loss or inconvenience.
The presence of mud can constitute a public nuisance and loss or injury can result in a claim for negligence.
Where a contractor is used, it should be clear who is responsible for the clear-up operation as well as who must put in place measures such as signs to minimise any deposits and risk.
If necessary a contractor should give an undertaking to this effect.
Earlier this summer, a woman injured when her motorcycle skidded on mud left by farm vehicles was awarded £10,000 in compensation.
Carrie Dickinson, 18, was riding her bike near her home in Belton, south Yorkshire, in October 2013.
The mud caused Miss Dickinson to lose control of the bike and she landed on her head and shoulder.
She suffered a broken collarbone, cuts, bruises and had severe concussion in the incident.
National law firm Hudgell Solicitors represented Miss Dickinson, alleging that the farmer had caused or permitted the highway to become or remain in a dangerous, defective condition, and a trap to anyone in that area.