Australia's deputy Prime Minister Barnaby Joyce said on Friday that he and Prime Minister Malcolm Turnbull might not always agree after he was elected in a Nationals party room ballot overnight.

Joyce was chosen by National Party colleagues after long-standing leader Warren Truss announced his immediate retirement from politics late Thursday.

Truss was leader of the Nationals - one half of the coalition - from 2007, and enjoyed 26 years in the parliament.

Speaking to Australian Broadcasting Corporation (ABC) radio on Friday, Joyce, who was deputy Nationals leader under Truss, said the coalition would be a formidable force with himself and Turnbull at the helm, but said there would be the "odd" occasion when he disagrees with the premier.

"We are a business partnership and not a marriage," Joyce told the ABC.

"At certain times the business partners have different views on things but I'm not going to go searching for them."

Joyce said he would continue to uphold traditional National Party values, namely, representing those outside of capital cities.

"People in the weatherboard and iron, people in the brick and tile, those on the farm, those on the coast who are saying well, 'these are the (politicians) who will represent us'," he said.

Meanwhile New South Wales senator Fiona Nash defeated six other candidates to take over Joyce's former position as Nationals deputy.

Also on Friday, Turnbull congratulated the pair on their appointments, saying he was "really looking forward" to working closely as a team.

"I'm very pumped up, I think it's a great result and I think this will be a very formidable team. We haven't got long to go to the election," Turnbull said.

Coalition colleagues have also praised the decision, with Christopher Pyne describing the pair as polar opposites - something he thinks will work well in Canberra.

"Malcolm and Barnaby are a great team because they're yin and yang in politics," Pyne told The Nine Network. "They represent all sides of the political spectrum."

Joyce will maintain his position in cabinet as minister for agriculture and water resources.