Australian farmers are asking themselves how they will grow a crop this year with an almost vertical rise in nitrogen fertiliser prices adding further to the doubling of phosphate fertiliser costs and tripling of some farm chemicals in recent months.

“Food prices are often blamed for high inflation across Australia," AgForce Grains president Lyndon Pfeffer says.

"But farmers know it is the increased cost of three inputs – fuel, fertiliser and chemicals – that is driving inflation.”

Mr Pfeffer says these costs will have major flow-on impact on the price of grain for human and animal consumption.

“AgForce identified a significant effect on returns a month ago when the price of phosphate fertiliser and glyphosate rose dramatically again," he says.

"Now the price of urea and other nitrogen fertilisers is increasing even more rapidly.

"And this has coincided with a 3pc or $100/tonne drop in the price of wheat at the farm gate over the same period.

“Fertiliser now represents about 50pc of the cost of production for grain in Queensland, whereas in the past, fertiliser represented about 25-30pc of the input cost, with the rest taken up by fuel, labour, weed control agents, seed and machinery.

“With China having increased the tariff it imposes on fertiliser from 20pc in February up to 136pc, the impact on the world market price for nitrogen fertiliser is now astronomical.”