The Turnbull government is planning a special visa to stave off a Nationals rebellion, address a shortfall of hundreds of thousands of farmers in the next decade and rescue billions of dollars in revenue.

The agricultural visa could also be used by ministers with sympathy for white South African farmers to encourage them to immigrate to Australia, as the issue continues to divide the highest levels of the Coalition.

"That would solve the South African problem," a government source said.

The preliminary stages of the visa have been in discussion for months after intense lobbying from the National Farmers Federation on the need to address a gap of 100,000 workers in the agriculture industry, but it is understood it is more likely to be announced months after the May budget.