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Hay-making equipment

Dennis Buckmaster and Stan McKee Published on 11 November 2009

Harvesting hay is the process of mowing a forage grass or legume, allowing it to air-dry thoroughly, then baling it into a round or rectangular package.

There are many variations and designs of machines that perform each step in this process and some that perform optional steps that may speed up or improve the process of drying.

This article will provide a basis for understanding the purpose of each machine, factors to consider for selection and some safety considerations.

Machine types
Hay harvesting begins with some type of mowing machine that cuts that forage. Once the forage has dried for a period of time, the hay may be fluffed up or spread out to decrease drying time before it is raked. The final step is the actual baling of the hay.

  • Mowers

These machines are used to mow the hay. There are basically two types of mowers: sickle bar and disc or rotary. The sickle bar type of mower provides a neat, clean cut of the forage. Speed limits how much forage can be cut in a given period of time because this type of mower can clog or may miss portions of the field if the tractor speed is too fast.

The sickle bar type mowers have a low power requirement, so smaller tractors can be used to run them. The disc or rotary type mower is good to use in lodged crops (crops that have fallen over).

Speed is not an issue with this type of mower because it almost never plugs. One drawback, however, is that it has a higher power requirement than the sickle bar type mower.

  • Conditioners

The conditioner performs a rolling or crimping function to the forage that will speed drying, and it is generally part of the mowing machine (mower-conditioner). There are two basic types of roll conditioners: rubber rolls or steel rolls.

The rubber rolls and the steel rolls both crimp and crush the hay stems with pressure. This process breaks open the waxy covering over the hay stem and allows the moisture inside to evaporate more rapidly. Hence, the hay crop dries down faster and is ready to bale in a shorter period of time.

Regardless of the type of conditioner, the more aggressive the setting, the faster the forage will dry, but at a cost of increased forage loss. Another type of conditioning machine is the flail, impeller or tine. These machines cut the forage with a scuffing action.

Because it doesn’t leave a clean cut, the forage plant can take longer to repair itself before beginning to grow again. Some mowers come equipped with a variety of extra features. Some of those features could include side windrow attachments for wider units, split swaths on wider units, cutter bar angle tilt adjustment, variable reel speed or suspension of cutter bar.

  • Tedders or inverters

Tedders are machines that spread the hay in the field for better air circulation. Inverters flip the swath over so the damp bottom is exposed to the sun and air for drying. This is an optional piece of equipment farmers can use to speed drying of the hay crop. It is typically used when adverse weather conditions slow drying so the hay cannot be baled before the next rainfall.

  • Hay rakes

Rakes gather and roll the partially dry hay into a windrow, allowing the underside of the hay to dry. It also allows the baler to efficiently pick up the crop for harvest. There are three types of hay rakes: parallel bar, rotary and wheel. The parallel bar has the lowest amount of hay loss, particularly with legumes.

They run on a ground or variable speed hydraulic drive system. Rotary rakes will sometimes come with dual functions. They can be used to rake or ted the hay. Wheel rakes save time because they can be operated at a higher speed than other rake types. One drawback to the wheel rake is that it has a higher potential for rock collection.

  • Balers

Balers pick up the crop in the field and compress it into a bale. Sizes of bales can vary depending on the machine. Small rectangular bales weigh approximately 38 to 40 pounds. Round bales can vary from 500 to 2,000 pounds. There are also very large rectangular balers that make bales weighing a ton or more.

Small rectangular balers come in a variety of sizes. Some small balers require manual bale stacking on the hay wagon, while others have a bale thrower that tosses bales into a hay wagon. Features you might find are hydraulic tension control, various pick-up heads and a pre-pack chamber.

Large round balers come in a number of different sizes also. The fixed chamber models have a soft bale core with high density on the outside. The variable chamber models have a more uniform bale density.

Machine capacity
There are four different factors which can limit the capacity of a machine to harvest hay. Depending on field conditions, power, throughput capacity, speed or traction can limit the field capacity of a machine.

Actually, in systems where machines must interact (such as harvest, transport and unloading), machine capacity can be limited by other machines. These limits to capacity are important concepts because harvesting quality hay can depend largely on timing. Mower conditioner capacity limits may be power, throughput or speed.

With disc cutters, often the tractor horsepower can be limiting. That is, if there were more power available, more acres per hour could be covered. In conditions with high yield and plenty of tractor power, the flail or roll conditioning system may be the limit to capacity.

In light yield conditions with adequate tractor power, speed may be the limit. This can particularly be the case with sickle cutters which do not perform well if travel speed exceeds six or seven miles per hour.

Raking, tedding and other swath manipulation equipment doesn’t require much power and, in most cases, can handle a tremendous volume rate of forage. There can be a trade-off, though, with excessive loss if you try to operate this equipment too fast or after the forage is below 35 percent moisture.

Like the mower-conditioners, baler capacity may be limited by power, capacity of the baler to “eat” and package forage or merely speed (especially if the field is rough).

Typical equipment sets
Matching equipment sizes and needs to the number of acres harvested can have a direct impact on the economics of making hay. Included below is a description of the machinery as well as labor requirement and cost per unit harvested for varying sizes of hay acreage.

  • Small rectangular bales: 100 to 300 tons dry matter (DM) per year (20 to 60 acres)
  • 9-foot mower-conditioner
  • rake
  • small baler
  • wo wagons
  • labor: 1.4 to 2.1 hours per ton of DM
  • Cost: $40-70 per ton of DM

Starting small with small rectangular bales, small machinery is sufficient.

  • Small rectangular bales: 200 to 400 tons DM per year (40 to 80 acres)
  • 8- to 12-foot mower-conditioner
  • tandem rake
  • medium baler
  • three wagons
  • labor: 1 to 1.4 hours per ton of DM
  • cost: $35-$50 per ton of DM

This section may seem repetitive, but notice the reduction in labor and cost per ton.

  • Small rectangular bales: 300 to 600 tons DM per year (60 to 120 acres)
  • 12- to 14-foot mower-conditioner
  • tandem rake
  • large baler
  • four wagons or automatic bale wagon
  • labor: 0.5 - 1.0 hours per ton DM
  • cost: $30-$40 per ton DM

An even larger, more automated system can reduce the labor requirement to 0.5 to 1 hour per ton of dry matter and cost in the range of $30 to $40 per ton of dry matter.

  • Large round bales: 100 to 300 tons DM per year (20 to 60 acres)
  • 9-foot mower-conditioner
  • rake
  • small baler
  • one wagon
  • labor: 1.2 to 1.4 hours per ton DM
  • cost: $44-$67 per ton DM

When moving from a small rectangular baler to a large round baler, we can see a decrease in the labor requirement. Cost is comparable between the two systems.

  • Large round bales: 200 to 400 tons DM per year (40 to 80 acres)
  • 8- to 12-foot mower-conditioner
  • tandem rake
  • medium baler
  • one to two wagons
  • labor: 0.9 to 1.1 hours per ton DM
  • cost: $36-$43 per ton DM

Labor for large round bales continues to decrease with larger acreage. Cost is still comparable between the two systems.

  • Large round bales: 300 to 600 tons DM per year (60 to 120 acres)
  • 12- to 14-foot mower-conditioner
  • andem rake
  • large baler
  • two wagons or truck
  • labor: 0.7 to 0.9 hours per ton DM
  • cost: $28-$33 per ton DM

As the acreage continues to increase we see a lower cost and less labor with large round bales and lots of forage compared to small square bales handled manually.

Harvest losses
No matter how carefully you harvest your hay, there will always be a portion of the hay lost during the harvesting process. DM isn’t everything. Quality matters.

When DM is lost, it is often the best part (leaves shattered, cell solubles leached). During mowing-conditioning we lose 1 to 5 percent DM, mostly from loss of leaves.

The conditioner design and setting can have a large effect on how much is lost. There is a trade-off in more loss for the faster drying rate.

Typical forage value losses
Hay harvest losses from raking will increase as the hay dries. Losses are highest when the field is low-yielding and after tedding. Losses can be as high as 20 percent in some fields.

The best practice is to rake the hay only once and that should occur on the day of baling. We can also expect to see losses from respiration and rain. These losses are highly variable but are typically a loss of the most digestible plant components.

To minimize respiration and rain losses we can use two strategies:

  • Try to always avoid rain.
  • Try to optimize the annual harvest.

Timing the harvest operations
Mowing-conditioning is the first step in hay-making and should occur based on the maturity of the crop and the weather. The crop maturity decision is based on finding an optimum between yield and growth stage. A

lfalfa hay should be mowed before the crop is in bloom, while grass hay crops should be mowed when or shortly after the plants shoot up seed heads. Most hay crops will take two to three days to dry in the spring when the plant is high in moisture and less time during the summer.

Listen to the weather report to find a time period when no rain is expected for several days. The other option to allowing hay to dry completely is to harvest the hay in a wilted stage and prepare it for silage.

Tedding is often done at the start of the second day after mowing in order to speed the drying time. Tedding or swath inversion can also be done after a rain to help the hay dry more rapidly.

Raking should be done when the hay has dried down to 35 to 45 percent moisture. It is best done on the day of baling, but may need to occur after a rain if the hay needs turned over to dry more quickly on the bottom of the swath.

Baling should occur only after the hay has reached the proper moisture levels. Proper small bale baling moistures for dry hay should range from 18 to 20 percent moisture. For large bales, the moisture should be 16 percent or lower.

Baling should occur only after the hay has reached the proper moisture for storage. There are products available on the market to apply to hay that has to be baled before it reaches the appropriate moisture levels. These products help prevent molding and heating when hay is baled too wet.

Hay-making safety considerations
Hay-making can be a dangerous activity; proper precautions should always be followed.

Here are a few considerations to keep in mind:

  • Shield disc mowers properly (knife tip speeds are 160 to 190 miles per hour).
  • Always use a tractor with a cab or at least a rollover protection system.
  •  Never stand behind conditioning rolls or flails.
  • Remember that baler flywheels and hydraulic accumulators store energy.
  • Keep fingers out of moving knotters (even if they are temporarily manually powered).
  • Do not ride the wagon when a bale thrower is used.
  • Handle bales safely.
  • Keep equipment “harvest ready.”
  • •Keep guards/shields in proper order.
  • Securely block hydraulically-raised equipment before working around or under the machine.
  • Disengage power and shut off engine before unplugging clogged equipment.
  • Keep a fire extinguisher on all powered equipment.
  • Do not allow kids or other riders on the equipment. [b:] FG

References omitted but are available upon request at

—From Penn State University extension website

Dennis Buckmaster
Biological Engineering
Purdue University