In early spring, you may have noticed bales of hay burning in a farmer's field while driving along a country road. This phenomenon is largely unknown to many passers by, and simply regarded as a farmer getting rid of unwanted hay. On the contrary, in early spring, green bales of hay under the right conditions will produce interior heat and combust on their own. This is a combination of microbial activity and a moisture content within the fresh hay of over 22 percent, according to an article in the Glasgow Daily Times and in a report from Washington State University. Properly removing these bales of hay and allowing them to combust is essential for the safety of the farm and a common practice among farmers.
Observe the hay in early spring, particularly the green-fresh bales. Look for rising steam or smoke above the hay that will smell like tobacco. Separate the dry brown bales from the green bales in the barn.
Check the interior temperature of the hay. You can do this by sticking a crowbar into the hay as deep as you can go. Pull the crowbar out after two hours and feel the end of the crowbar with your hand. If the crowbar is very hot and cannot be held for more than 10 seconds, the temperature of the hay has risen above 100 degrees.
Remove the green bales from the barn, carefully, using an appropriate machine, such as a fork lift or bulldozer. Move the hay away from any structures, livestock or loose debris. Place the hay in an open field away from anything that may catch on fire.
Separate the bales at least 10 feet apart from one another. When the bales combust, this will keep them from creating a giant fireball, which would happen if stacked close together.
Wait about three days while observing the hay. The hay should combust on its own within this time.
Allow the hay to burn out on its own. Attempting to put out the fire with water is futile as the hay burns at a high temperature creating an enormous amount of heat energy. The hay should burn out completely after about eight to 10 hours.