AUSTRALIA's farmers will face further price hikes for nitrogen fertilisers next year, following news of more lifts in export taxes for Chinese product.

In an attempt to keep more fertiliser onshore to grow crops, Chinese officials have again raised export tariffs, which will flow on to tightening worldwide supplies of urea.

China is the world's biggest urea producer and also exports other fertilisers.

Although most southern farmers have already arranged their supplies for next winter's crops, the move has implications for summer crop margins and next year's cereals.

There has already been talk urea prices will rise in the next few weeks.

Urea is currently selling for $930-$940 a tonne but one farmer said he had been told he had "better get in quick because it was going up $100 a tonne soon".

Just a year ago, farmers were paying about $450-$500 a tonne for urea.

Fertiliser Association of Australia executive manager Nick Drew said the last rise in Chinese export duties for fertiliser, in April, had an immediate impact on the world market.

"After that initial announcement, urea prices went up immediately, rising by $100 a tonne in a couple of days," Mr Drew said.

Victorian Farmers Federation grains group president Geoff Nalder said it was too early to be making predictions about fertiliser prices for next season but said there was a limit to what farmers would pay.

"If grain prices continue to fall and there is not a good incentive (price) to grow the crop, then it will change the mindset of some farmers, who may choose to do something else with their ground," Mr Nalder said.

"For those who are locked into cropping for whatever reason, talk of fertiliser prices going up is a concern."

Mr Nalder said China's decision to lift export tariffs was "disturbing to hear".

He said farmers would also look at other means of adding nitrogen to their soil rather than adhering to the cheapest methods such as urea.

He said some farmers had bought next year's fertiliser before the end of the financial year, but believed others would be too cash strapped to buy now to avoid any further increases.