Over 100l of diesel was drained from a tractor in a field in Newtown Cunningham, Co Donegal, last Thursday 17 November.
The theft took place overnight from a Valtra 4,600 which didn't have an anti-theft diesel fuel cap, the owner of the tractor Charlie Doherty told the Irish Farmers Journal.
The potato farmer from Moness, Burt, Co Donegal, said that they were harvesting potatoes that Thursday and left the tractor in the field to come back and finish the job the following day.
After driving the tractor for a short period the following morning, it stalled and subsequently air locked, despite there being more than enough diesel in the tank to do the day’s work, Doherty said.
"It's definitely something that should be highlighted to farmers. It was most likely locals; this field wasn't on a main road and it wouldn't have been that simple to get in.
"Conditions were sticky enough; you definitely wouldn't have got in in a jeep or car," he said.
Doherty says there's a possibility that a tractor came into the field and the diesel was transferred from one to the other.
A digger and another tractor, which were also left in the field overnight, had been tampered with, but no diesel was taken.
"We noticed the diesel cap was off the digger, but they couldn't get the diesel out because it had the anti-theft cap," he said.
Doherty, who sows about 160ac of potatoes every year, added: "Things are hard enough as it is without having this happen."