BROCKLESBY, Australia - Mr Justin Everitt is planting 50 per cent less wheat this year than he thought he would.

Standing in muddy brown boots and jeans by his tractor and 11m-wide seeding rig in a bare field, the 44-year-old said a lack of rainfall and rapid increases in fuel and fertiliser prices due to the war in Iran had ripped up his sowing plans.

He is one of thousands of farmers across Australia deciding to plant less wheat and spread less fertiliser.

Their choices – and the likelihood of a dry growing season for many - mean Australia, the third-largest wheat exporting nation, may have as much as 10 million tons less to ship in the upcoming season, an amount equivalent to 5 per cent of annual global exports.

Mr Everitt, whose family has farmed near Brocklesby, 300km northeast of Melbourne, for six generations, said he had never before made such radical changes to his cropping plans.

“Every indicator is pointing towards lower production,” he said.

A smaller harvest in Australia would reduce global wheat supply and put upward pressure on prices, which have already begun to rise.

Australia is the first major grain exporter to plant wheat since the beginning of the Iran war, which throttled exports of fuel and fertiliser from Gulf nations. Other countries are also likely to grow less, shrinking food supply further.

Reuters interviewed 18 farmers across Australia. In the driest areas, most were sharply scaling back planting. Nationwide, many were switching from wheat to crops like barley or canola that either need less fertiliser or sell for a higher price.

Forty kilometres west of Mr Everitt’s farm, near the town of Corowa, Mr Anthony Black said he would sow 20 per cent less wheat and use on...