Hay, Rain and Mold

Asked August 7, 2019, 11:57 AM EDT

A client called today to find an answer to a question about Hay that has been rained on. The Hay was fresh cut and green, it dried out and then it rained on the hay one time. It was left on the ground to dry out. Will this hay produce mold after just one rain fall on the hay? She thought maybe condensation/evaporation might affect the hay. She is looking for some info specifically about Hay that has been rained on once.

Clare County Michigan

1 Response

There are many factors that go into whether or not hay will have mold.

In my experience, baled hay will normally be moldy if the hay has excessive moisture at the time of baling. Another factor that will affect mold is the amount of soil trapped in the bale. I have seen this be a problem with hay that has been baled dry. I have also seen baleage (hay that is wrapped in plastic and baled at a higher moisture level) develop mold with the introduction of soil into the bale.

Even though the hay had rain fall on the cut material, given the fact that it was green is better than if it was just about ready to be baled.

If the ground is wet and moisture comes from the bottom of the windrow this can also affect the condition of the forage and cause problems with moisture.

The size of the bale is also a factor for proper bale moistures. Generally, dry hay should be 16-19% moisture in order to store well, remembering that the factors above will cause some variation.

Hopefully this answers your questions.