Tips for handling wet hay


By Sandra D. Smith

This spring and summer so far has proven to be very challenging for the farming community due to the weather. We went from extreme frigid temperatures this past winter, to a very wet spring that delayed field work, and put corn and soybean planting way behind.

Now, a very unpredictable storm season with flash flooding, hail damage, lightning strikes, high winds and tornados has had a negative effect on hay making and therefore the quality and quantity of the hay that is produced.

Damaged hay

Unfortunately, rain can damage hay in several ways. Rain leaches soluble nutrients and keeps the moisture level high, thus increasing the likelihood of decay and mold. Hay rained on during field drying of course damages legume hay more than grass hay and the drier the hay when rain occurs, the greater the damage.

However, delayed hay making due to concern about possible rain usually results in more forage quality loss than the actual rain damage itself. A big problem with rained-on hay can be the long-term damage that can affect not only the field but also the grasses as they start to grow back.

If the ground is still wet and soft when we are trying to work that hay to get it dry enough to bale, then we can cause soil compaction by repeatedly driving over the field. Windrows that are wet and left to lie in the field too long will smother or even kill the plants underneath the row.

This can cause an increase in the amount of weeds growing in the field that will decrease the quality of future hay crops. So do we bale that wet hay or not?

Must do something

One way or another we have to do something with that wet hay to minimize the negative impact it can have on our fields.

We can bale it but we need to also be cautious of the moisture content of the hay when baled and how we store it. Moisture content of round bales more than 18 percent and 20 percent for small square bales can cause excessive heating and possible fires.

Keeping this in mind, we could wrap or chop that hay. But if worst comes to worst and the hay is not good for anything but mulch, it can be chopped and left right on the field to help increase the organic matter of the hayfield.

Now that we have baled the wet hay there are some storage techniques that we can use that help minimize more loss from now until winter. Keep in mind that wet bales automatically increase in temperature after baling due to microbial activity and plant respiration inside the bale.

Bales also keep the heat of the day inside if baled during a hot day. Due to the heat that can be generated from these wet bales it is best to store them in an outside storage system to prevent structure fires from possible combustion.

Retaining nutrients

Keep in mind that we don’t want to lose any more of the hay’s nutrients then we already have and how we store that hay can prevent further losses. A partial solution or even preventative measure to minimize the amount of wet hay baled is to simply use a mower/conditioner and tedder on hayfields. Conditioning and tedding hay increases the drying rate.

Hay drying can also be sped up with commercial hay drying agents applied to each bale as it is baled but this process can be expensive.

Some round balers produce bales that sustain less weathering damage during outside storage than do other balers. Balers that compress hay more, result in a denser bale that sheds water better. In addition, the larger the bale diameter, the less total hay loss from weathering.

But be cautious, while increased bale density reduces spoilage by reducing moisture penetration, it also reduces the rate at which moisture and heat can escape from a bale. Making dense, evenly formed bales shed water better and sag less than a soft core or less dense bale.

Bale shape

Using net wrap or plastic twine spaced no more than 4 inches apart on round bales also helps to maintain bale shape and provides a smooth surface that encourages water runoff.

When stacking and storing rain damaged hay make sure that it is on a well-drained spot that prevents the bales from soaking up additional moisture from wet soil or standing water.

Using pallets, old railway ties, or anything that keeps the bales up off the ground will reduce the amount of the moisture they absorb.

Never place bales so that water runs off one bale soaking into an adjacent bale, if the bales are going to be left out with no cover.

These bales should be left in rows with the flat ends butted up together and arranged in rows that run north and south so that prevailing winds will not cause snow drifts during winter and so that both sides of the row can receive sunlight.

If bales are going to be stacked, make sure that they are arranged and covered as to prevent further water damage. As there seems to be more rain in the upcoming forecast, hopefully I have given everyone some reminders on how we can keep our forage quality up when dealing with that rain damaged hay to begin with.

(Sandy Smith is the Agriculture & Natural Resources Educator at the OSU Extension office in Carroll County, Ohio. She can be reached at 330-627-4310 or


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  1. Our 2nd cutting alfalfa was baled when dry, but that afternoon it got rained and hailed on heavily and is still in the field. What do we do with bales that were soaked by 3 1/2 inches of rain?

  2. Have same problem in SD. About one inch rain I need it for horses so will plan on giving to friend who has cattle. Afraid to feed it to horses. Bummer.


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