The Green Party's proposed carbon tax system initially exempts sheep and beef farmers because, unlike dairy farmers, they can't afford it, Greens co-leader Russel Norman says.
Dr Norman announced the party's Climate Protection Plan at the weekend and said under it, dairy farmers would pay $12.50 per tonne in emission charges. That would equate to 8 cents per kilo of milk solids, or a levy of $29.95 per cow.
Dr Norman said sheep and beef farmers would not initially be included because, unlike dairy farmers, they could not afford it.
Figures show dairying generates 42.9 percent of agriculture's emissions, while the sheep and beef industries combined account for 48.6 percent.
Dr Norman said economic analysis had shown that with the new tax, the bottom 10 percent of dairy farmers could be in trouble if the payout was $7 per kilo of milksolids.
"What they said is that the top, the 90 percent at the top, would be unfazed by this but the bottom decile, if the payout got towards $7 per kilogram of milksolids, could become vulnerable - but even they are still viable at that rate."