The Government has started reviewing the Emissions Trading Scheme (ETS) and opposition parties are again complaining about agriculture being excluded.
Climate Change Minister Tim Groser says the sector won't be part of the review and bringing it into the scheme is still off the table.
He says it won't happen until there are "viable and practical" technologies to reduce agricultural emissions, mainly methane from cattle.
The Government is putting millions into research and yesterday Prime Minister John Key said solutions could emerge within three to four years.
The Greens scoffed at that and said it would come as news to the scientists working on the problem.
"Agriculture must be part of the scheme," said MP Kennedy Graham.
"National is doing a long-term disservice to farmers who need to start having a discussion now about how and when they should be exposed to an emissions price."
The Greens don't believe the ETS works anyway and want it replaced by a carbon tax.
Labour also wants agriculture to be brought into the scheme.
The ETS puts a price on greenhouse gas emissions as an incentive to reduce them.
Industries generating emissions have to buy carbon credits, and when they achieve reductions they can sell them to those that aren't doing well.
It encourages tree planting, which is New Zealand's largest and cheapest form of carbon storage.
Critics complain that the Government's scheme is weak and favours industry, while ministers say they're not going to wreck the economy by putting unreasonable demands on industries.
However, a review discussion paper released by Mr Groser suggests industries could have to pay more in future.
At present they have to buy carbon credits for one in every two tonnes of carbon emitted, a level set when New Zealand was struggling with the impact of global financial crisis.
The discussion paper says there's a rationale for them to take full responsibility for their emissions.
Mr Groser won't commit to that but says the settings could be tightened.
Technical notes on the review will be released and submissions close at the end of April.
Proposals will be developed towards the end of next year.