600 tonnes of manure and straw have caught fire after over-heating.
Three crews of firefighters were called at 12.09pm today to tackle the blaze in Burwood Road, Stambourne, which was "ten to twenty minutes away" from spreading to a neighbouring crop field.
The pile belonged to nearby Warren Farm and was 25 per cent alight when firefighters arrived.
Crew manager at Halstead Fire Station Steve Byrne, who attended the fire, said: "The pile had been there for about a year and the heat at the bottom of the pile had built up to a temperature that sparked the fire.
"This is quite common throughout the summer with haystacks and can be devastating if nearby crops catch alight.
"As you can imagine, the smell was just awful."
The fire was extinguished by 3.46pm and nobody was hurt.