The shed burned to the ground, alongside a shelter belt and 2ha of crop, in the biggest blaze seen in Mid Canterbury for seven years.
About 20 appliances from throughout Mid Canterbury and further afield were needed to bring it under control.
The crop farmer, who did not want to be named, said he was grateful to the people and firefighters who attended the blaze.
He thinks it may have started from spontaneous combustion in a straw bale in the shed.
The farm was insured for the damage, which would cost hundreds of thousands of dollars.
The farmer said he was harvesting on Friday last week about 5.30pm when he was unloading a truck in the farm’s yard and noticed a small amount of smoke coming from the hay shed about 300m away.
"I hopped in the ute with the fire extinguisher and just hooned it over there," he said.
"It would have been less than two minutes from spotting the smoke to arriving at the shed.
"By the time I got there it was well alit, there was no coming back, it was just gone.
"It just erupted, it just went for it. Because the flames were so big, it just jumped into the hedge line."
About 20 fire trucks and tankers from Mid Canterbury, as well as Timaru, Geraldine and Temuka, attended.
They were on site for more than 24 hours as firefighters fought to bring the blaze under control and dampen down hot spots.
"We are very grateful for the community we are in to have such good guys around us," the farmer said of both the firefighters and others who helped out.
Tarbotton Land and Civil, also on Frasers Rd, had "dropped everything" to race to the scene.
Personnel from the business used the equipment they had on hand, as well as bringing in diggers they had at other sites around the district.
The fire engulfed several hundred metres of the hedge and about 650 large straw bales.
The cause is unknown but was likely spontaneous combustion, caused by moisture content, in a hay bale.
Burgess said the risk of further fires in Mid Canterbury remains "extremely high" with the dry weather forecast to continue.
