O'Connor said Poulton was well placed to tell New Zealand's agriculture and environmental stewardship story to the world.
"In the immediate term, her priorities will be engaging with farmer groups and other agriculture sector stakeholders to build support for our free trade agreement negotiations with Europe and, in due course, with the United Kingdom" said O'Connor.
"More broadly, Mel will be tasked with advocating for New Zealand's agriculture trade interests from the perspective of a practicing farmer and identifying opportunities for New Zealand to commercialise its agricultural expertise offshore".
Parker said Poulton would be "a passionate advocate for both farming and New Zealand products".
"I wish her well in this important role".
Listen to Jamie Mackay's interview with NZ's retiring Special Agricultural Trade Envoy Mike Petersen on The Country in the audio below:
Poulton will replace Mike Petersen, who has held the SATE role since 2013.
Ministers expressed their appreciation to Petersen for his commitment to the role over the past six years.
"Mike has made an outstanding contribution to New Zealand's agriculture trade interests, including developing an enduring network of industry relationships and helping to build
New Zealand's profile as a constructive and collaborative partner in agriculture to our trade partners" Parker.
Poulton will formally take up her role on 1 January 2020.
Meanwhile, Federated Farmers said it was "delighted" with Poulton's appointment, and looked forward to working closely with her.
Feds president Kate Milne said Poulton was "a great representative" of Kiwi farming, and had a good appreciation of the importance of trade to New Zealand and its primary sector.
"Mel can also handle a dog around a hillside better than any man I've ever watched, which should be an indication of the patience and skill she will bring to wrangling with international free trade agreements and getting good deals for New Zealand" said Milne.
