A barn fire in Surrey which destroyed £100,000-worth of hay was caused by spontaneous combustion of damp bales, an investigation has concluded.

The blaze at Potts Farm, near Farnham on 2 September, took 30 firefighters to put out. Crews remained at the scene for a further two days and a digger was brought in to turn the smouldering heap to break down heat spots.

Farm owner Matt Luard said that 800t of hay had been lost at a cost of £100,000 plus the building’s value.

Surrey Fire and Rescue manager Bryn Strudwick said: “Spontaneous combustion is rare but can be a real danger for farmers. A few simple steps can help to protect against the devastation this can cause to buildings and businesses.”

He thought the hay had heated to a temperature of 90C before it caught fire and he advised farmers to regularly check hay temperatures with a thermometer in the first few weeks after harvest.

Fire Service advice on storage –

• Hay and straw should be removed from fields as soon as possible after harvesting and stored
• Take care to ensure that it is dry to prevent spontaneous combustion
• Separate stacks from other buildings, particularly those housing fuels, agrochemicals and machinery
• Break down large stacks into smaller stacks spaced at least 10m apart
• Keep well below roof lighting

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