MANY Queensland vegetable growers may leave the land after suffering two floods in two years, a farmers' group says.

February is traditionally the planting season in the Lockyer Valley, west of Brisbane, which is known as Australia's beetroot capital.

But following the Australia Day long weekend floods, fruit and vegetable growers may be reassessing their future, says horticulture lobby group Growcom.

"There are going to be cases of people who cannot take the losses, there will be people who are forced off the land, and there are some who make a voluntary decision to leave," chief executive Alex Livingstone said.

"Because you have low prices, it's difficult to withstand the shock.

"Two shocks in two years is pretty hard."

Mr Livingstone said farmers, already struggling to recover from the 2011 floods, were now dealing with the loss of fertile topsoil, not to mention average crop losses of $300,000.

It takes up to four years for farming production to return to pre-flood levels.

Compared with 2011, the floods caused by ex-tropical cyclone Oswald were, in some cases, worse for farmers.

Two years ago, consistent rain preceded the heavy downpours.

This time, three days of heavy rain followed dry conditions, leading to the loss of more topsoil.

Crop damage has been particularly severe along the Laidley and Lockyer creeks, in the Lockyer Valley, damaging farms at Mt Sylvia, Mulgowie and Junction View.

Lockyer Valley mayor Steve Jones estimates the damage bill for future agricultural production is up to $500 million.

"There's the loss of crops and the loss of soil that can never be replaced," Mr Jones said.

Growcom predicts a more conservative flood damage bill, from Bundaberg to the Lockyer Valley, of $100 million based on losses for this financial year.

This includes damage to citrus crops along the Burnett River near Bundaberg and the Warrill Creek area southwest of Ipswich.