BUMPER crops and improved conditions saw confidence in the post farm gate agribusiness sector entered positive territory in December.

NAB's December Quarterly Agribusiness Survey showed the index reach positive territory for the first time since September 2010.

But those surveyed are tipping that confidence won't stay as solid into March.

The survey showed business conditions including profitability and employment increased 11 points to +2.

NAB Agribusiness general manager Khan Horne said the results were driven by seasonal conditions.

"The improved prospects for farming output managed to completely offset other concerns in the December quarter, such as ongoing strength in the Australian dollar, a weakening global economy and sluggish consumer demand," he said.

"This makes it very clear that the benefits of a strong season resonate much wider than the farm gate," said Mr Horne.

"Optimism for the next three month and 12 month periods weakened, with the index for expected business conditions declining six and three points respectively.

"Similarly, the index for business confidence remains squarely in negative territory at -13," said Mr Horne.

The survey found that profitability in the post farm gate sector in the December quarter was neutral, with equal proportions of respondents reporting either good or poor profitability.

"Profitability in this sector is being constrained by demand and the high AUD and there are still concerns out there for the March 2012 quarter with almost a third of businesses surveyed expecting poor profitability in the next three months," said Mr Horne.