Tips to avoid hay fires include:
- Consider seeding a grass mix with alfalfa as most grasses allow hay to dry more rapidly in the windrow and today’s improved grasses can still provide great feed quality and yield even for dairy farms.
- Provide good weed control as certain weeds tend to dry slower in the windrow than alfalfa.
- Know the proper moisture levels for safe baling of different bale packages and avoid the temptation to start baling too early in the day.
- Use approved hay preservatives if bales must be made wetter than what is advised.
- Properly adjust conditioning rollers on mowing implements to maximize drying without causing excess leaf loss.
- Utilize moisture testing equipment, such as handheld hay probes or in-chamber testing units on newer balers, to support decisions on when hay is dry enough to bale, but with a new unit always check it against another moisture testing process or unit as these systems can be highly variable in their results.
- Set aside any wet square bales in a separate location that will preferably be under cover and not in direct contact with the ground, but still allowing airflow around each bale, with non-combustible surroundings if possible.
- Use a thermometer probe, or in an emergency a metal pipe with a thermometer lowered inside, to check the interior temperature of a suspicious hay stack for two to three weeks after stacking; for temperatures 115 – 130 degrees F, monitor twice a day; 131 – 149 degrees F, check every few hours; 150 – 174 degrees F, have a good supply of water ready with extra help on hand and the fire department on standby and then pull out hot bales; 175 > degrees F, call the fire department, remove equipment and animals from the building, but do not pull out any bales until the fire department is on site (at this stage the introduction of oxygen into a hot spot in a stack is all that is needed for the hay to ignite and burn out of control within minutes).
- Do not walk on top of a hot spot as burned out cavities can cause cave-ins, instead lay down a ladder and walk on it when probing a hot spot.
The recommended moistures to bale without preservatives are:
- Small square bales (30 – 60 pound bales) - 14 - 18 percent moisture
- Large square bales (600 – 1,200 pound bales) - 14 - 16 percent moisture
- Large round bales (500 – 1,200 pound bales) - 15 - 19 percent moisture
Large square bales are more densely packed than other bale types and do not allow moisture and heat to escape as easily, thus the hay must be drier in those packages. In the Midwest it is difficult to dry hay to 16 percent moisture or less early in the afternoon so many apply a hay preservative like proprionic acid when large square baling begins in order to start baling earlier. Dry matter loss increases and forage quality decreases anytime we bale hay below 16 percent moisture, especially in round balers. Thus the optimum moisture ranges are the middle of the road between being too wet and too dry. In a good drying day a mowed crop of hay will pass through both ends of this range from 19 percent to 14 percent moisture in four hours so perfection in the making of hay bales is always a difficult target to constantly hit. But with knowledge and attention to detail farms can greatly reduce the risk of ever experiencing the loss of a hay fire.