I agree, which is why I said the farmer has either pegged it or his lease is up and there's no intention of ploughing or anything else.
He certainly wouldn't leave it fallow and pay rent for the privilege.
You leave the field untouched as there is no point turning it over until you need it, also it is easier to work and seed on fresh turned land.
As for the mud, if anyone deposits anything onto the highway then it is their responsibility to clean it up.
If farmer won't cleaning then the council will, then bill the farmer for the job plus a nice bit on top at council rates !
This is the same as hedges, cut your hedge back or the council will and bill the owner whether private house or land owner.
As a contractor for the council over the years I could charge a days rate for a compulsory job, be it hedges, roads or removing the stones people put to stop others driving on the grass, this was then billed out plus council's bit on top.
Nice earner when you do two or three a day !!
In legal terms mud is down to tractor driver or whoever, not the owner of the field.