Harvesting high quality hay and hay silage has been a challenge in a number of hay growing regions because of the unpredictability of rainfall. Rain falling on hay that's laying down in the field causes a number of problems. Soluble nutrients are lost, reducing feeding value and fermentation potential. Wet hay may also spontaneously combust. When properly dried forages should be ensiled at 65% moisture and bailed at 14-18% moisture (large-small bales). A number practices can reduce the amount of time that forages lie in the field.
Cutting implements that lay hay down in windrows 70% of the harvest width dramatically reduces drying time. The wide rows maximize the amount of area hay exposed to the sun and allow air to move underneath the swath. This maximizes the drying rate in Phase I (Figure 1) of the dry down process. This is very important because the plants will continue to respire and use nutrients while the stomata (holes in the leaves) stay open.
In dairy regions alfalfa cut in the morning and laid down in wide rows dries down to about 65% moisture about 5-7 hours later, ready to be chopped. Adjustments can usually be made to the mower to increase the swath width. If swath width cannot be increased to near 70% of the cut length, a farmer may consider borrowing or purchasing a mower that can lay wide swaths or hire a custom operator that can make wide swaths.
Figure 1: Sequence of Drying Forages: Drying Forage for Hay and Haylage, Dan Undersander, University of Wisconsin Forage Extension
There are two types of conditioners available to farmers: roller crimpers and flails impellers.
Roller crimpers are made out of rubber or steel. They are used to crush the stems of alfalfa to increase the dry down rate in Phases II and III. If alfalfa is being made into hay then it should be conditioned with a roller crimper. If the alfalfa made into silage it does not need to be conditioned if laid down in a wide row. Narrow rows (less than 70% cut width) should be conditioned whether the alfalfa is made into silage or hay. Before harvesting the rollers must be properly adjusted in order to crush the stems. Check your machines owner's manual or read "Mower-conditioner Adjustments for Rapid Forage Drying in the Field" for more information. Various crimper designs are available, but no consistent differences have been shown between the various designs in the dry down time.
Flail impellers are used primarily for grass hay or entangled forages. The deflector must be properly adjusted to ensure that the grass surfaces are cut by the flails. Impellers are not very effective tools to condition alfalfa.
Tedding, Raking, Inverting & Merging
Raking and tedding are two of the most well known practices to increase the dry down of hay in the field. They can, however greatly increase the ash content and leaf loss of the hay. Lower leaf lost occurs if the hay is tedded or raked between 40-65% moisture. If a farmer lays down a wide swath they could ted/rake the next morning, while a farmer with narrow rows would have to wait an additional day or two to reach this moisture content. Tedders and rakes should also be adjusted to minimize the amount of ash (dirt) they pick up off the ground.
Inverters and mergers are used to flip and merge the swaths. Inverters tend to pick up less ash than rakes or tedders. Mergers are used before chopping or bailing to merge multiple windrows (swaths) into one bigger windrow. Some drying occurs when the windrows are flipped, but not as much as wide windrows or conditioning operations.
Drying agents that can be sprayed forages can reduce the time needed to dry down hay. They are most often applied at cutting. The most effective products have potassium or sodium-carbonate based solutions. These treatments are most effective on alfalfa cut in the summer months. The drawback to apply desiccants is the large volume of liquid required to apply.
Preservatives are applied at bailing to ensure the quality of hay, often at a slightly higher moisture content (20-25%). When rain is coming and the hay isn't dry this can, applying a preservative can increase the harvest window and protect hay that may get rained on. The most effective preservatives on the market are made from on proprionic acid. Many mixes of other organic acids (acetic acid, etc.) can work well, but proprionic acid based products are the most reliable. It is applied at 1-2% of hay weight.
Disc Mowers vs Sicklebar Mowers
No difference in drying rate is noticeable between disc and sicklebar/cutterbar mowers.
To read more detailed information click on the titles of the references below.
Drying Forage for Hay and Haylage
Dr Dan Undersander University of Wisconsin-Madison
Effectiveness of Equipment to Speed Hay Drying
C. Alan Rotz, Agricultural Engineer USDA-ARS, University Park, PA 16802
Mower-conditioner Adjustments for Rapid Forage Drying in the Field
Ronald T. Schuler, Wisconsin Extension Agricultural Engineer
Making and Storing Quality Hay
Jimmy C. Henning and Howell N. Wheaton, University of Missouri Extension Department of Agronomy
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