However, if the moisture content is 22% or above, it can cause problems - both to the quality of the hay and the risk of spontaneous combustion and fire."Check stored [bales] regularly. If there is a smell of caramel or a distinct musty smell, it is likely that your hay is heating. Continuing, the NIFRS said: "Hay can spontaneously combust if the temperature within the stack rises above 55°. The stack may need to be dismantled.
Avoid storing hay in sheds containing fuels or chemicals and separate from livestock."Ensure sufficient space between the top of the stack and electrical lighting," the fire and rescue service concluded.