Departmental secretary Daryl Quinlivan and his senior executive colleagues have tried and failed four times to convince their 4600 public servants to accept the deal.

But the Community and Public Sector Union ridiculed the departmental leader's claims on Wednesday, saying they were "petulant".

The historic no-vote is part of a fresh wave of rejections by large public sector workforces of the Coalition's workplace policy with public servants at the Department of Immigration and Border Protection the giant Department of Human Services both voting against proposed agreements and scientists and researchers at the CSIRO knocking back a deal for the first time ever.

Further resistance by smaller agencies like the National Museum and the Administrative Appeals Tribunal means there is no end in sight to Turnbull government's industrial war with its public servants as it enters its fourth year.

Public servants at Mr Turnbull's own department, The Prime Minister and Cabinet have vote-no twice and the unrest has now reached into the offices of Coalition MPs and Senators with a number of their staffers campaigning against the new pay and conditions proposal they have been offered.

But in an email to his staff on Tuesday, Mr Quinlivan said the continued impasse was the fault of the CPSU and its "misleading commentary", while he offered workers "the real information" on the deal they were asked to accept.

"I am concerned that at least some of the 'no' vote has been influenced by misleading commentary from the CPSU, including about the Senate inquiry, leave entitlements and moving conditions to guidelines," Mr Quinlivan wrote.

"Much of the CPSU's commentary on these issues is untrue and cannot have been motivated by advancing your interests.

"We have corrected misinformation on these issues along the way and made this information available ... but clearly need to do more to ensure you are properly informed."

Mr Quinlivan made it clear he would try to make it fifth time lucky for his workplace proposal after trying again to gauge the reasons for the four no votes.

"With the time and money already lost and not recoverable, my intention at this early stage is to try again to make the case for a long overdue pay rise, and to do so soon," he wrote.

"But firstly I am keen that you are given opportunities to more directly provide feedback on your motivations for voting 'yes' or 'no', so we can make informed final decisions on next steps."

CPSU national secretary Nadine Flood ridiculed the idea that her union was able to convince workers to vote against their own interests.

"We'll be making it clear to Mr Quinlivan how disappointed our members are with his petulant response to this embarrassing fourth bo vote," she said.

"Agriculture staff are smart, well-informed and more than capable of making up their own minds.

"As I've said before, the idea the CPSU has some magical power to make people vote against their own interests and that of their families after three long years is ridiculous."