Storing round hay bales outdoors presents a significant challenge because high spoilage rates are directly tied to moisture absorption from both the top and the bottom of the bale. Unprotected hay stored outside can experience dry matter losses ranging from 5 to 35 percent, depending heavily on local climate and storage methods. The outer layer of a large round bale, which can account for roughly 25 percent of the total volume, is most susceptible to weathering and microbial activity. Implementing strategies to minimize moisture exposure preserves forage quality and maximizes the return on the initial investment.
Preparing the Storage Location
The initial defense against spoilage involves isolating the bales from ground moisture, which can account for over half of the total dry matter losses. Bales resting directly on the soil act like a wick, drawing moisture upward and creating an environment for mold and bacterial growth. Selecting a site that is well-drained and slightly elevated is the first step toward successful outdoor storage, preferably featuring a gentle slope to encourage water runoff.
The storage area should be open to full sunlight and wind, avoiding low-lying areas or shaded spots near tree lines, which slow the drying process after precipitation. Creating a physical barrier between the hay and the soil prevents wicking action and can reduce storage losses by approximately 5 percent compared to storing bales directly on the ground. Effective base materials allow air to circulate freely beneath the hay, ensuring moisture does not become trapped and accelerate decay.
Base Materials
Effective base materials include:
- A four to six-inch layer of coarse gravel or crushed rock, which provides excellent drainage and airflow.
- Wooden pallets.
- Old tires.
- Railroad ties.
Optimizing Stacking Orientation
The way bales are arranged physically encourages water shedding and maximizes air circulation to reduce spoilage. For outdoor storage without full cover, the single-row method is preferred over pyramid stacking, which funnels water from the top bales directly into the lower ones. Pyramid stacking increases contact points, traps moisture, and causes the bottom bales to sag, increasing soil contact and wicking.
The recommended method is to position bales flat end to flat end in a single, tight line. This arrangement minimizes the surface area exposed to weather and prevents rain or snow from penetrating the vulnerable flat ends of the bales. Placing these rows in a north-to-south orientation allows for maximum sun exposure and drying across the length of the row throughout the day.
Maintain a minimum of three feet of space between adjacent rows of bales. This spacing ensures sufficient air movement and sunlight penetration, helping the bales dry quickly after rain. Keeping the vegetation mowed between the rows further enhances airflow and prevents moisture retention near the base of the bales.
Covering Options for Weather Protection
Protecting the bales from overhead precipitation is the final step in reducing dry matter loss, which studies show can be reduced by up to 50 percent with plastic covering. The outer four to eight inches of the bale are the most vulnerable, and a proper cover ensures the bale maintains its structural integrity and feed value. The choice of covering material depends on the desired level of protection and cost considerations.
Plastic net wrap, applied during the baling process, is a common first line of defense that creates a smoother, denser bale surface compared to twine. This tighter surface sheds water more effectively and helps the bale maintain its shape, reducing sag and subsequent ground contact. Net-wrapped bales can reduce dry matter losses by a third compared to bales secured with twine when stored outside.
For complete weatherproofing, heavy-duty tarps or specialized plastic sheets shield the entire stack from rain and sun. These covers should be made of durable, UV-resistant material like high-density polyethylene or PVC fabric to prevent degradation. The cover must extend past the widest point of the bales, allowing water to drip clear of the bale base and onto the ground, preventing runoff into the bottom layer.
Securing the cover is as important as the material choice itself, as wind can easily lift and tear loose tarps, exposing the hay to moisture. Covers must be anchored tightly using ropes, straps, or specialized tie-down systems to prevent flapping during strong winds. Some producers opt for individual bale sleeves or bonnets, which offer tailored protection for single bales, though often at a higher per-bale cost than a large group tarp.