After mowing a forage crop, the next step in the hay-making process is drying forage to a suitable content for end use. Forage intended for dry-hay production should be at 20% moisture or less before baling. Hay baled at the correct moisture decreases the risk of spoilage and hay fires while maintaining nutritional value (Krieger, et al., 2021). If baleage or silage is the intended product, the moisture can be much higher, but usually not over 60%. 
Fast dry-down of hay after mowing is important for several reasons. The primary concern with hay drying is to avoid rain in the forecast. Figure 1 shows the probability of rain in the days that follow cutting hay. Ohio typically has a 3- to 4-day window to get hay mowed, dried, and baled before the next rain. Additionally, fast dry-down preserves the nutritional value of the forage. Mowed forages continue to respirate until plant moisture falls below 60%, at which point the stomata close which stops the respiration that preserves feed value (Undersander & Saxe, n.d.). Stored carbohydrates and sugars are depleted during respiration, leading to a loss of nutrients. The faster a hay crop is dried, the more nutrients the forage will preserve.
Choosing the wrong piece of equipment or using a machine incorrectly can directly decrease hay quality. Leaf loss and ash (dirt) incorporation are major concerns during the drying and raking process.
Minimizing External Ash Content and Leaf Loss
External ash content in hay is typically from soil disturbances during the hay-making process. Higher ash content results in lower feed quality, so minimizing soil contact is necessary to produce high-quality hay. Proper equipment settings to reduce contact with the soil will reduce the amount of ash in baled forages.
The type of rake you choose also can influence ash content. Research comparing different hay rake types has shown that wheel rakes introduce significantly more external ash than bar or rotary rakes (Neu, et al., 2017).
Wheel rakes form a windrow of hay using ground contact to spin the wheels, and they inevitably pull soil into the windrow in the process. This research also showed that mergers are the best option to reduce external ash content in baled hay. High ash content in forage may have negative impacts on livestock performance, so choosing the correct rake can have economic impacts beyond the initial purchase price.
Much of the nutritional value of a hay crop is found in the leaves of the plant. This is especially true for legumes, so leaf loss during the hay-making process results in lower-quality feed.
Strategies to minimize leaf loss:
- tedding immediately following mowing
- raking with a dew on the windrow
- choosing a drying method that is gentle on the hay crop
Generally, the drier the hay crop during tedding or raking, the higher the rate of leaf loss.
Tedders
Drying hay starts with proper mower and conditioner settings, and using wide swaths (Ruff, et al., 2025). Several pieces of equipment can be used after mowing to aid in the drying process. Hay dries from the top down in the swath. Inverting or spreading out the swath will speed up the drying process. Using a hay tedder soon after mowing can reduce drying time by about 1–2 days (Rotz, 1995).
The two main types of tedders are rotary and fluffer. Rotary tedders use a series of counter-rotating arms with attached tines to lift and spread the hay from the field. This action exposes more of the forage’s surface area to sunlight and air movement, but it is also an aggressive process that can lead to leaf loss if used on dry hay—especially legume crops.
Fluffer tedders use vertically rotating bars with tines to lift hay from the windrow and then set the hay down in the same area. This action aerates the hay (increases air flow for drying) and is less aggressive than rotary tedders. The gentler action of fluffer tedders reduces the risk of leaf loss.
Tedders can be sized to fit any operation from an 8-foot working width to over 50 feet for large operations. The smallest tedders generally cover one hay swath at a time and require a tractor with a power take-off (PTO) higher than 30 horsepower (HP). As the size of the tedder increases, HP requirements increase, and hydraulics are typically used for folding the tedder for easier transport and storage.
Tedding is an effective tool to promote drying, but repeated passes over the hay crop may increase ash content and lead to leaf loss. To minimize ash content, tedders should be set to pick up mowed hay without contacting the soil. As mentioned, tedders are aggressive machines and multiple passes over a field may result in higher leaf loss.
Hay Rakes
When hay reaches the appropriate moisture for baling, it needs to be collected into windrows sized to the baling equipment. Raking high-moisture hay (greater than 30%) is more easily accomplished with rotary rakes or mergers rather than wheel and bar rakes because wheel and bar rakes tend to form clumps of dense hay that can be difficult to bale. Hay rakes are the most common method for gathering hay, but specialized hay mergers are also popular for larger farms with alfalfa crops. Smaller rakes typically clear a swath of less than 10 feet and work well with small square balers that typically have a lower hay capacity than larger round-balers or large square-balers. For larger balers, or thin hay crops, a larger capacity rake will make the raking and baling operation more efficient. V-style or center-delivery rotary rakes can limit your ability to adjust windrow size compared to a side-delivery rake.
Many types of hay rakes are available, but the most common is the parallel-bar rake due to its availability and relatively low price—especially on the used market. These rakes function by rotating parallel bars with rake teeth that gather the hay and deliver it to one side. Although PTO and hydraulically driven options are available, the most common form uses a ground drive through a gear box or some other mechanical drive from the wheels. Without a PTO, parallel-bar rakes can be used with many types of equipment and the ground speed can be adjusted more easily for crop conditions without worrying about PTO speed. Bar rakes tend to gather the hay and twist it as it is delivered to the side. This is called “roping,” which can reduce air flow and increase dry time.
Wheel rakes are increasing in popularity. These ground-driven rakes gather hay when the rake wheel touches the ground at an angle, allowing the forward movement to turn the wheels and move the hay to the side. These rakes can be as small as two wheels that attach to a three-point hitch, or as large as a 20 wheel (or more) pull-type rake. Larger wheel rakes can move a lot of hay, which requires an increased handling capacity for any large round or large square balers being used. These rakes are popular due to the ease of maintenance (few moving parts), adjustable windrow size, lower cost, and higher speed of raking. Wheel rakes rely upon ground contact for operation which can result in higher ash and damage to stubble. Correct settings are necessary to reduce the amount of uncut forage pulled into the windrow, which leads to increased drying time.
Rotary rakes are also a popular choice with many hay producers as they are generally gentler on the hay crop. Rotary rakes have a large rotor with arms attached that carry rake tines. As the rotor moves the arms in a circular motion, the tines lower to the ground, rake the hay into the windrow, and then the tines lift to release the crop.
By minimizing tine contact with the ground, rotary rakes generally contribute lower ash to hay than wheel rakes. Their raking action also results in a fluffier windrow that promotes additional drying.
Rotary rakes are operated by PTO, so the ground speed needs to match the correct speed for the crop. Single-rotor rakes (up to 15 feet in diameter) work well for small to medium-size farms, but multiple-rotor machines are available for larger capacity jobs. Compared to bar or wheel rakes, rotary rakes are generally more expensive to purchase and are more mechanically complex.
Mergers
Hay mergers are popular options for dairies and farms that process a lot of hay. Mergers operate by picking up the hay with tines and placing the hay on a moving belt that deposits the hay into a windrow. Large machines can merge up to 30 feet of hay into a single windrow. Reversing belts allow hay to be deposited on either side of the machine, resulting in the ability to create large windrows that are well suited for forage choppers.
Mergers do not move hay across the ground, so ash content is typically lower and leaf retention higher when these machines are used. Mergers are the most expensive option, and are not economically viable for most small to medium-sized farms.
Summary
- Use wide swaths and proper mower settings to promote rapid drying.
- Employ tedders soon after mowing to reduce drying time, but avoid multiple passes to minimize leaf loss and ash.
- Choose rake types carefully: rotary rakes reduce ash and improve drying, while wheel rakes offer speed but may increase ash.
- Adjust equipment settings to minimize soil contact and preserve forage quality.
Additional Resources
- Forages, Ohio State University Extension
(forages.osu.edu/home)
References
Krieger, D. A., Sulc, M. R., Weiss, B., & Underwood, J. (2021). Hay preservatives. Ohio State University Extension.
forages.osu.edu/sites/forages/files/imce/Hay%20Preservatives.pdf
Neu, A. E., Schaeffer, C. C., Undersander, D. J., Hall, M. H., Kniffen, D. M., Wells, M. S., Catalano, D. N., & Martinson, K. L. (2017). Hay rake-type effect on ash and forage nutritive values of alfalfa hay. Agronomy Journal, 109(5), 2163–2171.
doi.org/10.2134/agronj2017.03.0185
Rotz, C. A. (1995). Field curing of forages. In K. J. Moore, & M. A. Peterson (Eds.), Post-harvest physiology and preservation of forages (Vol. 22). CSSA Special Publications.
acsess.onlinelibrary.wiley.com/doi/10.2135/cssaspecpub22.c3
Ruff, G., Corboy, T., & Beers, L. (2025). Purchasing hay equipment: Forage mowers [Fact sheet]. Ohioline, Ohio State University Extension.
ohioline.osu.edu/factsheet/anr-0186
Undersander, D., & Saxe, C. (n.d.). Field drying forage for hay and haylage. University of Wisconsin-Madison.
dairy.extension.wisc.edu/articles/field-drying-forage-for-hay-and-haylage