Prime Minister Scott Morrison announced this week that four department heads would lose their jobs, as the number of departments shrink from 18 to 14.

Ms Ley and Senator McKenzie will keep their jobs as ministers and continue working in their individual portfolios, within the single department.

Farrer MP Ms Ley told The Border Mail she had no concerns about the changes, which will come into effect in February.

"Government policy and portfolios routinely work across different departments and this restructure is simply designed to improve how we can better deliver the growing number of services each of us expect as taxpayers," she said.

"Our environment works hand in hand with farmers and the agriculture sector in many different ways, so I actually see a number of advantages with the move. Bridget and I are both in Cabinet so we are well aware of and welcome these changes."

IN OTHER NEWS:

One department head to be sacked is Communications and Arts secretary Mike Mrdak, who became associated with the North East rail line when he fronted Senate Estimates in 2017.

It was Mr Mrdak who first revealed the cost of the upgrade would be "considerably upwards" of the $134 million already spent on the ballast rehabilitation program.

A year later, the federal government allocated $235 million to the project.

Mr Mrdak was later moved to his new department and The Age has reported that he slammed the government's decision on mergers in an email to staff this week.

"We were not permitted any opportunity to provide advice on the Machinery of Government changes, nor were our views ever sought on any proposals to abolish the department or to changes to our structure and operations," he said.

Border Rail Action Group chairman Bill Traill was disappointed with Mr Mrdak getting sacked, saying his revelation about the costs "was an enormous breakthrough for BRAG" at a time when it was tough to get information.

"Mrdak is now a victim," he said.