A farmer who had about $40,000 worth of irrigator tyres slashed thinks the act of vandalism is designed to send a message about irrigation in the Mackenzie Country.
The police said 44 tyres were slashed with a knife on Richard Subtil's farm in North Otago early on Saturday morning.
Mr Subtil and his wife Annabelle own a 12,000 hectare high country merino and beef farm just outside Omarama and were one of two farms to win the South Island Farmer of the Year title in 2015.
He said the damage was upsetting.
"Initially it's the sheer shock of finding that many tyres and three machines needlessly vandalised.
"It just makes you feel pretty sick that this is somebody's way of sending a message, whether it's personal or environmental it seems pretty sad that this is what it's come to."
There had been a lot of conflict over irrigation in the Mackenzie Country, he said.
"The irony is that we would be known locally as being on the green edge of what we do and we're quite outspoken about trying to limit inputs et cetera.
"We've recently installed three lysimeters to measure the output so we're pretty scientific about that sort of thing. The nature of what we produce means we are low output system anyway - maybe people see them [irrigators] on the side of the road and make an assumption."
Mr Subtil said the damage was likely to be covered by insurance.
Kurow's senior constable, Craig Bennett, said tyre marks showed a vehicle was driven onto Mr Subtil's Omarama farm to get to the three pivot irrigators early on Saturday morning.
He said the vandal or vandals would have been there for some time.
"They've had to climb over an electric fence to get at one of the pivots and then it's been a matter of walking backwards and forwards with a lot of commitment because the irrigators were going so they would have been getting absolutely drenched at the time."
Mr Bennett said he was unsure whether the vandalism was targeted at the farmers personally or was a statement against irrigation.
He said anyone who saw a vehicle or lights in a paddock near Broken Hut Road just outside Omarama early on Saturday morning should call the police.