One of four harvest fires in Cambridgeshire over the weekend was started deliberately.
Investigators said 12 acres of crops in a field on Bell Road, Bottisham, was set alight on Saturday.
Two crews from crews from Cambridge, the south roaming fire engine, one crew from Newmarket and one crew from Cottenham took more than three hours to tackle the blaze.
“The cause of the fire is believed to be deliberate,” said a fire service spokesman.
Fire crews are warning people to be extra careful in the hot weather to prevent fires at home or in the open after battling four fires, two of which were arson and two accidental.
“Our crews attended a number of outdoor fires over the weekend. Fires can start and spread quickly in this hot, dry weather.”
The most serious of the weekend blazes was two acres of straw and hedgerow at Great Wilbraham on Friday.
A spokesman said: “Crews arrived to find two acres of standing straw and hedgerow alight.
“Firefighters used hose reels and beaters to extinguish the fire, before returning to their stations by 6.40pm.
“The cause was accidental.”
On the same day, fire fighters were called to Hoghill Drove, Haddenham, where they found hay bales alight.
The area was re-inspected over the weekend by crews from Ely and Cottenham, to ensure it burnt out safely.
At Harlton on the same day at 7.35pm, two crews from Cambridge, one crew from Cottenham, and one crew from Linton were called to a stack fire on Washpit Lane.
Working for almost 12 hours with the farm, firefighters created a water shuttle and worked in sections while using two hose reels and beaters to extinguish the fire.
All crews returned to their stations by 8.10am the following day.
The cause of the fire was accidental.
On Sunday (22) at 2.59pm, one crew from Chatteris and one crew from March were called to attend a fire in the open on London Road, Chatteris.
Crews arrived to find half an acre of grass well alight.
Firefighters used two hose reels and beaters to extinguish the fire before returning to their station by 9pm.
The cause of the fire was accidental.
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