A trade union representing farm workers fears the Government's zero hour contracts legislation could cost thousands of labourers their jobs.
While many unions have criticised the legislation for not going far enough, Amalgamated Workers' Union's secretary Calvin Fisher said the opposite was true.
He said the Government was bowing to union pressure, and not taking into account agriculture, where casual employment was necessary.
"It's ironic that you're trying to get middle ground here... it's typical of Government legislation that tries to put a framework around employment situations and there's not one situation that covers all," he said.
Under the Employment Standards Legislation Bill, employers would not be able to cancel shifts without giving plenty of notice.
If they did, they would have to pay their workers compensation, unless they allowed them to work for someone else if a good offer came up.
Mr Fisher said that was rarely feasible, and the new rules could end up costing people their jobs.
"Any circumstance where there's not product and workers are wanting to be paid something for nothing, it becomes a very complicated situation," he said.
"Eventually, if the employer isn't getting the revenue, how can he pay the wages?"
Former National MP Phillip Burdon, who owns the country's biggest mushroom farm, Meadow Mushrooms in Christchurch, agreed.
He said the banning of zero hour contracts would force him to pay employees on days when work was impossible because of the weather.
"Industries where there's clearly flexible hours and weather dependent, appropriate consideration must be made," he said.
"If you've got an outdoor crop and you're trying to pick lettuces and it's raining like hell, you can't do it."
Council of Trade Union lawyer Jeff Sissons said a rainy day was not the worker's fault.
"The fundamental question here is, who bears the risk when work can't go ahead? Our view is that businesses are better placed to bear this risk than workers," he said.
"You can't predict the weather day to day, but over time you can.
"Many farmers are paid minimum wage - we're not talking about well-paid workers here."
Mr Sissons said the bill needed to be clear about how much compensation would be paid.
Labour leader Andrew Little said the legislation's purpose should be stopping employers holding workers by a thread - but it needed to be distinguishable from casual employment.
"I go back to the days when I did a bit of haymaking on farms around Taranaki, if it was raining, you didn't get the work. When it was fine, you worked your butt off," he said.
"That was the way it was, but it worked for everybody. The most fair thing is to say we have casual employment, it's worked and it'll work again."
Workplace Relations Minister Michael Woodhouse refused to be interviewed, sending Radio New Zealand only an outline of what was in the bill.