DESPITE a flood of generic farm chemical brands available at highly competitive price wars during the past decade, Australia's average grain property chemical bill soared from just $44,000 in 1991 to about $194,000 in 2012.
Grains Research and Development Corporation (GRDC) northern region manager Sharon O'Keeffe said while fuel, fertiliser and chemical costs had all made big rises, the chemical story stood out.
"Some chemical products like glyphosate are certainly much cheaper than 20 years ago, but the chemistry we rely on in many other products is much more costly," Ms O'Keeffe said.
"We're also working harder with a wider range of products to kill weeds more effectively because weed problems are more diverse and farmers must act more decisively and effectively to protect this season's yields or avoid longer term weed issues.
"And while glyphosate might be cheaper, the trend to minimum till means we use a lot of it."
The average annual farm fuel bill in GRDC's Queensland and northern NSW region had jumped from $39,000 20 years ago to $98,000 between 2009 and 2012.
Fertiliser costs were up from $33,000 to $92,000.
An increasing trend in farm sizes had accounted for some of the cost hikes, while declining natural soil fertility had generally required more fertiliser inputs.
The GRDC figures were based on average northern region grain and livestock farms of 5400 hectares.
However, Ms O'Keeffe said the trends were similar to responses to GRDC's surveys across Australia where the average responding farm size was about 3400ha.
Farm labour costs were up about 30 per cent on 20 years ago to average $215,000 according to Ag Profit analysis.
Ms O'Keeffe noted the survey responses would have generally under valued the real cost of a farm owner's labour input, especially given more farmers today had tertiary qualifications that could command much higher pay rates than they paid themselves.