Taranaki-King Country MP Shane Ardern will not seek re-election next year.
After serving the electorate for 16 years he is going back to farming.
"Now it is time to spend more time with my family and return to farming fulltime. Family and farming is where my heart lies," he said.
Mr Arden was first elected in a by-election in 1998, and initially ran to represent the rural community in Parliament.
New Plymouth MP Jonathan Young said Mr Ardern had been a successful advocate.
"As one of the few dairy farmers in Parliament, Shane's voice has been critical to that industry. He has done very solid work around the DIRA [Dairy Industry Restructuring Act] legislation and brought a clear understanding of its implications to our caucus and Parliament."
"Shane was always great to work with and he was able to give me solid advice as a new MP, which I appreciated," Mr Young added.
Mr Ardern's most notorious career moment was driving Myrtle the tractor up the steps of Parliament in 2003, in protest against the introduction of methane omission taxes.
Mr Ardern said another highlight for him was being involved in the legislative process for Fonterra.
"It has given me great satisfaction to see policies I have worked on - particularly in the dairy industry, biosecurity, forestry, and rural New Zealand - passed into law," he said.
He said having two sons come back to farming had been an incentive to leave his position, but said he also faced other challenges. "I physically or financially can't afford to be here anymore," he added.
Harry Duynhoven, the former Labour MP for New Plymouth, said he enjoyed working with Mr Ardern over the years, and wished him well for the future.
"It would have been a difficult decision. He had a loyal support base and strong majorities over the years," he said.
"He looked after the interests of his electorate."
In 2011 Mr Ardern received nearly 70 per cent of the vote.
The MP was also the chair of the primary production select committee, and National's agriculture caucus, and said he had worked on policies that have "helped drive New Zealand's economic recovery".
Mr Ardern will continue to work for the electorate until next year's election.
- © Fairfax NZ News
How much would you pay for a seat on the coastal walkway?