With even the best hay, a lot can go wrong between baling and feeding. Common-sense hay storage practices, however, will minimize spoilage.

Hay Enemy Number One: Moisture

UV rays often bleach nourishment from hay bales, and rodents destroy a certain percentage of stored hay by chowing down on the more delectable varieties or simply nesting in the bales. Such challenges, however, are preventable or manageable with the help of indoor hay storage, good housekeeping and barn cats. Heading off the damage from excessive moisture is more complicated.

Even when baling takes place at the optimum time, with a moisture content below 20 percent, all hay bale in their first few weeks. Plant cells in the hay continue to  for a while after cutting, and microbes naturally present in the field interact with plant sugars and oxygen.

Those processes can breed mold. The risk of mold doesnt stop after the sweating period, especially if hay bales are exposed to rain and snow during hay storage. More and more farmers in both the United States and Canada are producing large round bales. Because of their unwieldy size, those bales are often stored outdoors. It is not uncommon for farmers in wet, humid areas of the United States and heavy snow areas of Canada to lose the outer 4 to 8 inches of their round bales to mold. Rain, snow and wet ground conditions can thus destroy 25 percent of round bale tonnage–losses many farmers can’t afford.

With indoor hay storage, losses rarely exceed 8 percent. But that percentage can increase significantly with poor barn conditions.

Indoor Hay Storage Tips

Many hay producers and their customers wait up to three weeks after baling before they store hay inside barns. Others only partially fill their haylofts during the sweating period, to allow for good air circulation. Such practices reduce the risk of fire, not just mold. The chemical processes involved in plant cell respiration generate heat. In the early weeks, new bales typically have hot spots in excess of 120 degrees. In densely packed, humid conditions, that core temperature can exceed 200 degrees, with the real risk of spontaneous combustion.

Even after the sweating period, bales stored on the barn floor benefit from air circulation beneath the bottom tier. Wood pallets and railroad ties are cheap ways of raising the bales off the ground.

But even elevated hay bales can wick up moisture from a wet barn floor. Ideally, the floor should crown somewhat higher than the surrounding terrain. Roof gutters and French (ground) drains around the exterior of the barn can further ensure a dry floor and healthy bales.

Round Bale Hay Storage

A little elevation can similarly minimize dry matter losses in round bales stored outside. Farmers often use railroad ties, old tires and rocks as platforms for the giant bales. Another trick is to take advantage of slopes, to drain water away from the hay. Some farmers opt for the so-called Canadian method, sacrificing a lower tier of round bales, positioned cut-side-down, to serve as a platform for a top row of round bales, lined up end to end.

Where space is limited, round bales may be stacked in triangles. Farmers with adequate space, however, generally arrange round bales in a long line, end to end, in a north-south direction. This arrangement ensures maximum sun exposure. In addition, at least three feet of space should separate the long rows, to guarantee good air circulation.

Some farmers tuck their round bales under trees, in hope of protecting them against rain and snow. In reality, however, this hay storage arrangement only increases moisture content, by depriving the bales of sufficient sun and air circulation.

Another taboo is stacking round bales side by side. This is particularly risky in snowy Canada and the northern United States. This arrangement creates mini-valleys that hold in snow and rain.

The Cover Controversy

Round bales wrapped in netting before field storage generally stand up to the weather better than twined bales. The tighter the bale, the more resistant it is to weathering.

Less porous coverings — whether a sausage-link sleeve connecting several bales or a tarp pinned down over the bales — may be of less value, however. Heavy plastic coverings, in particular, can restrict air flow and thus increase the risk of mold. One Canadian study, carried out in Alberta in 1988, showed higher losses for plastic-wrapped round bales than for unprotected bales.