Producing High Quality Dry Hay

The unique balance of harvesting the hay during between the rains and minimizing stand damage in saturated soils may be a tough. For some producers, choosing to harvest their forage as silage bales (baleage (PDF 242 KB)) might be a better option than trying to get dry hay off the ground.

The primary goal in forage production is to preserve the quality until it can be fed. Harvest losses will often derail your plan for top quality forage. Losses can range from 10% for grass hay to as high as 35% for legumes, but these can be avoided by understanding where they commonly occur. Following are a few of the common loss sources during dry hay production and how to avoid them.

Pre-Baling Operations

Conditioning – Freshly cut hay is typically 80% moisture, and must lose about 6,000 lbs per acre of water for each ton of hay to reach 20% moisture. Conditioning can speed drying by opening the waxy cuticle layer surrounding the stem and allowing moisture to evaporate faster. Be sure your conditioner is adjusted correctly to maintain adequate roll pressure uniformly along the entire roll length. Apply sufficient roll pressure to the hay to cause a noticeable breaking of the stem skin, but not so much pressure that leaves are broken off. Proper adjustment of rollers can keep dry matter losses down to 1% to 3%.

However, conditioning slows cutting and requires much more horsepower and energy than raking. One should consider not conditioning, and rather cut with a wide swath (minimum of 70% the cutting width), increasing the speed of travel (up to 20-28 mph) and plan on raking the swath after a few days of drying. The result is typically similar time spent haying while using less energy and putting up higher quality hay. If conditioning is used, raking should take place within 24-48 hours after harvest.

Raking - Raking is typically done to put two or more windrows into one. However, more leaf loss can be caused by raking hay than by any other harvest operation when done too late. Avoid raking legumes when the forage moisture is less than 35 to 40%. If the rake is PTO driven, synchronize field speed and PTO speed to provide a gentle lifting and turning action. This will avoid aggressive handling of the forage and excessive leaf loss.

To form bales of consistent density and shape, make windrows uniform in width and uniform in the amount of hay contained. Field loss occurs as a bale turns within the round bale chamber, so don’t create unnecessary bale chamber loss by running the baler when there is no hay feeding into the chamber.

Wheel rakes are the most common type of rake on the Prairies and should be adjusted properly to avoid the high ash content in the hay. The height should be set just above the ground level. Paralell bar rakes can leave the forage “beat up” if travelling too fast – they should not be used for producing dry hay – rather only silage hay.

Tedding - Tedding fluffs, spreads or moves the windrow of hay, but should be done when the hay is still moist (at least 40% moisture) to reduce leaf loss, especially on legume hay stand. Some tedders simply shift the windrow several feet onto a dryer area while others spread out, invert and/or fluff the windrow. All these operations may improve drying, but the risk of leaf loss is high. This operation is better suited to grass hay fields, where dry matter losses are minimal. An alternative is to cut with a wide swath without a conditioner and rake prior to 40% moisture.

Macerators – Macerating crushes the stems and leaves of a plant, increasing the drying rate – occasionally resulting in the stems drying faster than the leaves. They are a useful option, however, they are an additional pass on the field (wheel traffic always reduces yield potential), slow and expensive.

Moisture Content – Hay moisture content is the largest single factor contributing to leaf loss. Hay baled above 15% has much less leaf loss.

When hay becomes too dry and brittle and losses become excessive, stop baling and resume in the evening or morning when the leaf moisture level increases. This dew-moistened hay can be baled at a slightly higher moisture level than when it was drying down because dew moisture in the hay is more easily released during curing than internal moisture.

The upper moisture level depends on the type of hay, density and size of bale, drying conditions after baling, and other factors. The upper limit for moisture for large round alfalfa bales is typically 18 to 20 percent. Hay baled much above 20 percent moisture will usually spoil unless chemical preservatives such as propionic acid are added to the hay. Effective hay preservatives will prevent excessive heating and mold growth when applied uniformly and at the correct rate. Wet bales are not only at risk for spoilage, but also fires; don’t take a chance if you’re uncertain. 

Rained on hay accrues losses via the following ways:


  • Leaching of soluble carbohydrates and certain minerals (protein often not significantly affected).
  • Mild/long-term rainfall events will remove more soluble nutrients than short-term/intensive rainfall events. As much as 50% of the dry matter removed might be soluble carbohydrates. These carbohydrates are what feed the microbes in charge of ensiling, thus losing them can reduce the option to ensile the crop. Additives can be used to supplement lost carbohydrates, but this adds cost.
  • Increased and prolonged plant respiration
  • The plant continues to convert collected carbohydrates to C02 gas until it reaches 30% moisture. Re-wetting the hay above 30% moisture will essentially restart the respiration process.
  • Leaf shattering and loss from continued handling (eg. raking) to dry the swath, along with frequent wet-drying cycles increase the leaf drop.
  • Microbial activity. Wet hay will support continued microbial breakdown of plant structure and nutrients, and promote the development of molds.
  • Color bleaching. Continued exposure to the sun and elements will result in the loss of green color, thus reducing marketability.


The Baler

The baler pickup will typically create a 1 to 3% loss, but can be as high as 12%. Field speed, size of windrow, hay moisture content and mechanical condition of the pickup mechanism (broken and bent pickup teeth) accounts for this range.

Higher moisture content reduces pickup loss, so avoid baling when the hay is overly dry, especially legumes. Synchronize your ground speed to pickup speed to reduce this loss.

Another area of potential loss is the bale chamber. In general, bale chamber losses are normally two or three times higher in a large round baler than a rectangular baler. To minimize bale chamber losses, the moisture content should be as high as possible that will allow for safe storage. The forage should be fed into the baler as fast as possible to minimize the number of turns within the bale chamber. A high feeding rate can be attained by using large windrows and high forward speeds. If the windrows are small or field speeds must be slow, reduce the PTO speed which results in fewer revolutions to form a bale.

Finally, when wrapping twine, do not rotate the bale more times than necessary to secure it. The fines, primarily leaves, which fall from the bale chamber during twine wrapping, are an indication of the bale chamber loss. These fines contain the highest level of nutrients, so minimizing these losses is important.

How Baling Wet Hay Affects Storage Management

Due to the unpredictable weather, many producers may end up baling hay a little wet. When storing these bales, it's important to note that bales automatically increase in temperature after baling due to microbial and plant respiration inside the bale; generally up to about 54 0C. Bales also keep the heat of the day inside if baled during a hot day. Therefore, if you plan on storing hay inside a building (eg. hay for export), it is at risk of spontaneously combusting when baled at 18% moisture or greater.

To counter the risk of heating and mold development, some producers have added natural enzyme-based additives in hays baled above 20% moisture; others have stuck with using more traditional acid-based additives. If you have assumed some risk in baling this years hay a little wetter than normal you need to MONITOR YOUR STACK while being aware of the details below. If you've baled wet hay that is at risk of heating, leave the hay unstacked for the first 3 weeks after baling, allowing the heat to escape.

If you do stack the hay, use a temperature probe to measure heat. Probe the stack in several places, making sure to reach the middle (therefore may need 2-3 foot long thermometer). Buy one that can read up to at least 95 0C.

The cheaper option is to build your own from 1/2" - 3/4" steel pipe. Pinch one end and drill 3 to 4 small holes in the side of the pinched end to allow air flow. Then weld a T-shaped handle on the other end. Then simply slide a glass thermometer on a string down the tube which is stuck in the stack. Check your stack as frequently as possible; once a day is a good place to start. If temperatures are rising, consider pulling the stack apart to cool it off. Be sure to check the most tightly packed area in the bale as this is where the temperatures will first begin to rise. For example, check within 6-12" from the center of a round bale. Use the temperature ranges below to determine the risk of losing the quality of your bales to heating.


  • Up to 49 0C: Caused as fungi and bacteria carry out normal respiration. The process is referred to as normal sweating during hay curing. This temperature rise occurs when hay is baled at 15-20% moisture. These temperatures generally do not cause serious concerns in forage quality loss. However, mold may develop at this temperature range. 
  • 43-65 0C: Caused by fungi able to grow at this temperature range. Chemical re-actions during heating will denature some protein and cause some fiber to be less digestable.
  • 57-71 0C: Caused by fungi respiration. At 65 0C, check temperature every day. At temperatures above 71 0C, chemical reactions dominate the heating process. If the temperature continues to rise, check it every four hours. At this stage, the situation may become dangerous.
  • 79 0C: Continue to check the temperature every few hours and notify your local fire department. Do not attempt to move the hay without fire department assistance.
  • 90 0C or more: Spontaneous combustion is possible. Ask your fire department to assist you.
Source: North Dakota State University; South Dakota State University; Iowa State University Extension