 CFA attends around 150 haystack fires every year. The number one cause of haystack fires is when hay containing too much moisture spontaneously combusts. And it can just take one damp bale to ignite a whole stack. But with a few simple steps, you can minimise the chance of your investment going up in smoke. Hay overheats when there's too much moisture within the hay. If it's green, for example, or if it becomes damp before, during or after baling. The moist environment is favourable to fungi and bacteria, whose biological and chemical processes generate heat, similar to that in compost. This heats the bale, and if left unchecked, will get hotter and hotter. If the hay reaches 70 degrees, it can rapidly increase to the point of spontaneous ignition at around 180 degrees. Preventing a haystack fire starts with cutting the hay. You shouldn't bale hay until it's fully cured. This varies depending on the crop and the type of bale being used. An easy way to check moisture is to use a correctly calibrated moisture metre as you're baling. The next step is to protect hay from rain, leaking roofs and spouts. Cover stacks with tarps or hay caps. If storing in a shed, don't stack all the way to the roof. Leave some space for ventilation. A useful strategy when it comes to storing hay is to limit the size of haystacks and place them in different locations, so they're not all stored in the one place. This will prevent you from losing all your hay if a fire does happen. It's also a good idea to put a fuel break around each stack. You should regularly check your haystack to make sure it's not overheating. If you have one, use a temperature probe to check the temperature inside the haystack. An effective alternative is a crowbar inserted into the haystack. If after two hours the crowbar is too hot to hold, the temperature is over 70 degrees and likely to spontaneously combust. If the haystack heats to over 60 degrees, you should carefully pull it apart to improve airflow and allow it to cool down. You should be careful when doing this however, as hay may be very hot. If the temperature is over 70 degrees or if you smell smoke or a caramel smell, do not pull it apart as you may introduce the oxygen needed to ignite the hay. Call 000 and ask for fire.