Four Western Bay dairy farmers have broken employment laws in recent years, according to workplace watchdogs.
A trade union leader is citing the breaches as evidence the farming sector is "out of control" and needs to be more accountable.
Information released to the Bay of Plenty Times under the Official Information Act showed labour inspectors began investigations at nine Western Bay of Plenty farms between July 2012 and February this year and found four had breached at least one employment law.
One dairy farm resulted in the Ministry of Business, Innovation and Employment labour inspectors taking enforcement action. The inspectors achieved compliance during or after their visits to the other three farms.
Federated Farmers Bay of Plenty president Rick Powdrell expected ignorance was the cause of most breaches.
"Three out of four farmers complying fairly easily tells me it was probably a case of a lack of understanding by the farmers," he said.
"Staff working long hours at certain times of the year need to be paid accordingly but then there's things like what is and isn't an acceptable time sheet."
The ministry and farmers needed to work together to make improvements, Mr Powdrell said.
"Farmers can't hide behind a lack of knowledge. They need to get up to speed but it's got to be clear what being up to speed is ... If you actually get out there and help and educate you tend to get more people on board than if you wave a stick at them and say 'you're not getting it right, you need to get it right'."
Nationally, 165 farms were found to have made at least one employment law breach.