The Green Party says it will pay more than $136 million for farmers to move to more sustainable practices.
The move announced this morning is part of the party's plan to protect New Zealand's waterways.
Its leader, James Shaw, said the party wants to stop the causes of water pollution and will pay farmers to help them move to less polluting, more sustainable and profitable ways of operating.
He said the party, if it were in government, would invest in the Sustainable Farming Fund and introduce a fund to support organic farming alongside a new sustainability accreditation scheme.
Mr Shaw said this would be paid for by a nitrate pollution levy on dairy farmers who continue to pollute the soils and water.
He said nitrate pollution was already measured by a modelling system called Overseer.
"The average dairy farm would pay no more than five percent of their pre-tax profits. So that's the average and it would be no more than that. What's really important is that farmers would be able to get that money back by applying to the funds that we're setting up."
The Green Party would also place a moratorium on any more farms being converted to dairy, and instead support organic farming.
Mr Shaw said the policy would tackle the cause of polluted rivers and not just the symptoms.