Prime Minister Jacinda Ardern announced the "historic consensus" on Thursday morning in Wellington, gathering with primary sector groups to reveal the deal.

Missing were environmentalists, who panned the agreement as too slow, and a climate sell-out.

That didn't dampen Ardern's enthusiasm for the 'He Waka Eke Noa' deal, which she said was all about creating change that "will stick".

"For too long politicians have passed the buck and caused uncertainty for everyone while the need for climate action was clear," Ardern said.

"I'm proud that we have a world-first agreement ... and we've done that by reaching a historic consensus with our primary sector."

Dairy farmers and primary industries have been granted major concessions by Ardern's coalition government as it ramps up action to combat climate change and equip its economy to adapt to change.

The agricultural sector contributes roughly half of New Zealand's emissions, making it a major part of any climate policy negotiations.

In a win trumpeted by farmers, they will receive a 95 per cent discount rate when slotted into the ETS, a concession championed by minority coalition partners NZ First.

Individual farms will be asked to report emissions from 2023, required to report them in 2024, and start paying for them in 2025.

The deal had origins in an industry proposal put by several peak bodies, including Dairy NZ.

"We are grateful you have engaged with us and listened to us," Dairy NZ chief executive Tim Mackle said.

Environmental group Forest and Bird said the move was a step in the right direction "but the change is far too slow".

"We need all industries to do everything they can to reduce greenhouse gas emissions right away," chief executive Kevin Hague said.

Greenpeace went further, saying Ardern's government had rolled over for the primary sector and "sold out" Kiwis.

"The government has buckled to lobbying pressure from the diary industry and big agri-business," campaigner Gen Toop said.

"Agriculture is our biggest climate polluter. An emissions trading scheme without the sector in it is a joke and won't be able to combat the climate emergency - the greatest threat humanity has ever faced."

In a speech to the United Nations last month, Ardern pledged to make New Zealand the world's most sustainable food producers.

"We've been asked to try and create change that will last. We have been having the debate for 15 years. The debate has to end. The action has to start," she said.

"That's what this is about today. This will stick.

"For those that say that we're not doing enough, well, this is a world first. No one is pricing agriculture. No one is doing this work, farm by farm.

I'm incredibly proud of what we're doing here today on behalf of New Zealand."

Australian Associated Press