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0807 PD: Machinery requirements for making baled silages

E. Raymond Thompson Published on 02 August 2007

Equipment needs for baled silages are quite simple. Mowers do not need to have conditioning rollers, but mower-conditioners are useful because they concentrate the cut forage into a narrow swath.

These narrow swaths allow baling without raking. If the mower leaves a wide swath, it should be raked to ensure adequate pickup into the baler.

Since the forage is wet and heavy, bale diameters generally range from 42 to 48 inches to avoid overloading either the baler or the transport equipment. Bales should be formed as tightly as practical.

Some people believe belt-type balers make a more uniform bale than chain-type balers, but no research supports this claim. Fixed-chamber hay balers lack the flexibility of variable-chamber balers to vary bale diameter as a means of reducing bale weight in wetter crops. Fixed-chamber silage bales have smaller diameters.

The ground speed of the baler should be lower than speeds used in making field-cured hay. Downshifting one gear should help to guarantee a tighter, denser bale. A dry matter density of 10 pounds per cubic foot is considered ideal. A typical silage bale (4 feet in diameter by 5 feet in length) should weigh 1,300 to 1,550 pounds and contain 600 to 650 pounds of DM, but it may weigh as much as a ton.

Some baler manufacturers recommend retrofitting older balers with kits that aid in baling wet forage. Many manufacturers produce balers designed specifically for making baleage.

Some recent models of both fixed and variable chamber balers include knife mechanisms to chop the forage, allowing increased density. University of Kentucky research found that using a “chopping” fixed-chamber baler increased silage bale weights by about 300 pounds at the same bale diameter.

Traditional bale spears can be used to move round bales of silage, but they have the disadvantage of puncturing the plastic, if the bale is moved after wrapping. Wrapping the bales after they have been moved to their place of storage will avoid puncturing the plastic.

Another more expensive option is the hydraulic bale squeeze that mounts on a front-end loader. This implement allows the movement of wrapped bales without making holes in the plastic. Tractors with 50 or more horsepower have sufficient weight and power for safe lifting.

Bale-wrapping and bagging equipment
There are many ways to seal freshly baled forage, including individual bags, tubing machines and individual or group bale-wrapping machines.

All operate on the principle of quickly sealing out oxygen from the bale and keeping it airtight until the baleage is fed. Use of plastic manufactured to withstand the damage from ultraviolet radiation in sunlight is strongly recommended. Some plastic manufacturers recommend using untreated sisal twine or plastic twine. In some cases, the oil from treated sisal twine breaks down the ultraviolet radiation inhibitor in stretch-wrap plastic.

Using individual bags has two advantages:

  • extra equipment is not required
  • bags can be reused to reduce cost

In practice, however, few bags can be salvaged for use in the next growing season. Disadvantages include the difficulty of getting all of the air out of the bags and maintaining a good seal on the open end of the bag. Making baleage in individual bags is less reliable than with wrapping equipment.

Rodent damage also appears to be more prevalent with individual bags compared to wrapped bales. Round bales can be loaded mechanically into long plastic tubes that are mechanically stretched during loading and then allowed to contract. This process aids in getting a good seal around the bale.

The number of bales per tube is flexible. (Plastic can be cut and sealed.) Disadvantages include the need for a uniform ground base for tube placement (if large) and sizing bales to the tube. Also, a hole in a long tube exposes a large amount of silage to potential spoilage. Finally, large bales stored in tubes are less portable than individually wrapped bales.

The most popular form of baled silage is individual bales wrapped mechanically with four layers of stretch-wrap plastic. Each layer of stretch-wrap plastic adheres to the previous one, forming an airtight seal.

Wrapping machines vary widely in cost ($4,000 to $15,000), depending on such features as whether they produce a completely wrapped bale and whether they include a self-loading arm.

The cheapest wrappers require a second person (or getting off the tractor) and manually moving the roll of stretch plastic while the bale is rotated on a spear, much like twine is applied to round bales of hay. The plastic is lapped over the ends of the bale about 12 inches.

Single or multiple bales can be sealed by manually stretching plastic across the exposed ends. Jamming multiple bales together (flat end to flat end) allows the plastic from one bale to stick to the next, forming a tube. A uniform, level soil surface is necessary for good bale-to-bale contact and the maintenance of a good seal.

More expensive wrappers completely cover each bale by elevating the bale onto a rotating and revolving platform. Some have hydraulic lifts to elevate the bales onto the platform. Others require a second tractor with lifting capabilities to put the bale on the wrapper.

Other considerations
Damage to plastic during handling or storage allows oxygen to enter the bale, causing spoilage. Any holes made during bale transport and placement into storage should be repaired immediately by taping. Holes allow oxygen to enter and lead to problems with silage quality due to aerobic deterioration.

To minimize storage losses due to spoilage, bagged silage bales should be fed to livestock during the winter following their production. Do not feed silage that has significantly deteriorated or has a bad odor. Silage that improperly ferments from being too wet can lead to botulism poisoning.

To prevent this, do not make silage at moisture contents above 70 percent. Exposure to oxygen can also lead to deteriorated silage and animal toxicity. Unrepaired holes or having too few layers of stretch-wrap plastic can lead to oxygen infiltration of the bale.

The ability to make baleage allows for the harvest and storage of the fall alfalfa cut or other forages that come in some years. In most years, this forage goes unused unless these fields can be grazed since curing conditions are too poor to get the forage dry enough to bale as hay.

Ensiling conditions are not ideal during this time (low temperatures and low numbers of ensiling bacteria), and fall baleage should be fed first during the winter. Silage inoculants have been shown to improve the ensiling characteristics of fall forage crops.

The interval between baling and wrapping or bagging is critical to the success of the ensiling process and should be as short as possible. Prior to wrapping, high-moisture forage is subject to very high respiration rates and to the growth of undesirable microorganisms.

Respiration reduces forage quality by consuming readily digestible carbohydrates. Significant increases in bale temperature are also associated with excessive delay between baling and bagging of silage bales.

Data from the University of Missouri illustrates the importance of rapid bagging after baling. Based on this data, even an eight-hour delay between baling and bagging resulted in greater temperatures during storage compared with those bales bagged immediately after baling.

Consider moving freshly baled forage to the storage area for wrapping. This allows the wrapping process to be done on more level, uniform ground. Bales can “walk off” the wrapping platform if the machine is not level.

Minimizing movement of wrapped bales will reduce tearing of the plastic. Wrapped bales can be speared for movement, if these holes are resealed.

Consider identifying different types of baleage and different cuttings by marking with spray paint. Different colors could represent the various crops while the number of marks (dots or Xs, for example) could indicate the cutting.  PD

References omitted but are available upon request.

—From Russell County Extension Newsletter, Summer 2006