Spring is one of the most fuel-intensive seasons in rural Australia — farmers harvesting around the clock, trucks hauling grain to silos and markets — and diesel prices are rising again just as it begins, the ABC reports. The timing stings: crops in Victoria, New South Wales and South Australia are on track for bumper yields, with harvest already underway in central Queensland and the rest of the country to follow in coming weeks.

"We're getting a bit of deja vu where the price seems to be heading north again," said Victorian Farmers Federation president Ryan Milgate, who warned the diesel price would "really, really bite on the bottom line". Growers already paid more for fuel and fertiliser during sowing earlier this year. "We sort of can't get a break here," Mr Milgate said. "We're looking at double the price of diesel that we were paying 12 months ago." And there is no workaround, in his telling — "diesel is the only option" to bring the harvest in: "I haven't seen pedals on a header yet and I don't really like the concept of that either."

$275,000 a month from a Melbourne depot

Dan Russo runs a fleet of 13 semi-trailers and road trains from his base in Melbourne, and says the return of high diesel prices is "crippling the trucking industry". "You've got 10 trucks taking 1,000 litres minimum each day," Mr Russo said. "Not to mention the extra repair bills due to the roads, extra running costs, registration, tolls." The higher prices come out of his pocket: "[In June] when fuel hit $3.20, our fuel bill was just under $400k," he said. "July, our fuel bill dipped down … August, it's gone back up to $275k."

His warning is aimed at every shopper. "The more you hit the transport industry, the higher your consumer prices are going to be," he said. "No-one wants to see $10 bottles of milk at the supermarket."

In the Mallee, the worry is supply, not just price

Simon Barbary farms at Woomelang in Victoria's Mallee, and fuel cost is only his second-biggest concern. "We've got to have it so unfortunately we're just a price taker. You can't say no as much as you want to," Mr Barbary said. "If more ships get taken out, we'll be filling everything we have no matter the price." He needs about 15,000 litres of diesel to get through harvest — a volume his on-farm storage can hold — and says he'll now look at seriously building up his supply, "but that depends on price, I guess". The season itself is the bright spot: "If we weren't looking at these sort of yields, we'd be in a hell of a lot of trouble." The catch is that big crops burn more fuel: "The machinery is working harder, more truck trips to the silo, so yeah we will probably be using 10-20 per cent more fuel."

Commodity market analyst Andrew Whitelaw said fuel is still flowing into Australia. "The numbers are still showing pretty strong flows coming into the country," he said. "We're probably about 5 per cent down year on year." But he described the situation as becoming "precarious" as the US-Iran conflict continues. "The reality is that stockpiles around the world are starting to get a little bit more constrained," he said. "If we start to see October volumes starting to look very sort of constrained ... that's when we have to start worrying and panicking."

That makes the next few weeks a strange kind of waiting game across Victoria's grain country: a bumper crop standing in the paddocks, and everyone watching the price of the one thing needed to bring it in. "Low grain prices and high input prices," as Mr Barbary put it — "that's what keeps me up at night."