A vote for the Green Party does not necessarily mean a vote against farming, co-leader James Shaw says.

Shaw disagreed with The Country host Jamie Mackay's suggestion that a Labour-Green coalition government was bad news for agriculture, saying it was a "myth perpetuated by the other side".

"They'll say Greens are bad for the economy and that they'll destroy the government."

Shaw believed his party had demonstrated an understanding of farmers over the past three years and said he had two points to prove it.

"A - that we understand that volume to value strategy for New Zealand farming.

"B - we've invested hundreds of millions of dollars in supporting that strategy at the farm level and with agricultural organisations."

Entering into a partnership with the agricultural sector on greenhouse gas emissions last year also showed that any criticism was "just noise", Shaw said.

Mackay's suggestion that Shaw wasn't "hard-left enough" for some of his party members was also discounted.

"You can say that, but they keep voting me as the co-leader and they do that every year. Every party has got its squeaky wheels - we've got ours as well."

Meanwhile, Shaw told Mackay he disagreed with Dr Jacqueline Rowarth's opinion piece, "Does fewer cows mean more money for farmers?".

In the piece, Rowarth suggested that some environmentalists would be happy to have no cows at all in New Zealand, an idea that Shaw said was "nonsense".

"The whole strategy of our agricultural sector is to move from volume to value ... the sector itself is saying what we want to do is to get greater value for our products.

"We estimate we've got about enough land to feed 40 million people - which of course is not even close to the eight or nine billion that are currently on the face of the planet.

"So what we can do, is take our historical advantage and high-quality farming and keep pushing that and keep innovating the way that we always have and to create greater value for our products.

"It's not always about volume. In fact sometimes pursuing a volume strategy actually gets in the way of that and you end up with a more low-value commodified product."