Large round bales have been a popular hay package for many years. To see them piled or rowed outdoors along fields and buildings has become a part of the rural landscape in many parts of the country. Outdoor storage is convenient, but it's not always cheap. Some bales will largely maintain their forage weight and quality, others will not. But why?

Storing round bales outside is a bit like driving a car down the interstate. Outdoor storage allows you to drive just a bit over the speed limit by not using indoor storage. However, pushing the pedal to the floor with outdoor storage is going to result in a hefty fine, just as it eventually will on the interstate. In the latter case, it’s a speeding ticket; in the former, it comes as forage dry matter and quality loss.

Though the positive economics of indoor storage are well documented, the reality is that round bales will continue to be stored in Mother Nature's full view. To that end, let’s focus on best practices for outdoor storage and leave the barn-building lecture . . . well . . . in the barn.

Storage losses accumulate pretty quickly when you consider that the outer 4 inches of a 5-foot diameter bale account for at least 25 percent of the bale’s dry matter. Research studies have documented dry matter losses on outside-stored bales from less than 10 percent to over 30 percent. Here's how to be on the low end of that range:

• Use net wrap rather than twine. Aside from a shorter wrapping time, net-wrapped bales shed water better, and research documents that dry matter losses will be cut by about one-third compared to twine. Sure, net wrap costs more but it’s an easy cost recovery when you consider the feed and time savings.
  
• Make dense bales — it’s a no-brainer that they shed water better. Perhaps more importantly, they sag less so that there is reduced bale-to-soil contact (if stored on bare ground). Much of the storage loss often comes on the bottom of the bale.
• As with real estate, location is important for outdoor bale storage. A rock base is ideal, but if that's not practical then select an area that is well drained and subject to good air movement. Never store bales under or along a tree line.
• Tightly stack bales end-to-end. This reduces end spoilage. Reducing end spoilage by 2 inches per end per bale saves about a 5-foot wide bale of hay for every 16 bales in the line.
• Leave about a 3-foot space between bale rows to enhance air movement and drying.
• Run bale rows parallel with the slope. Rows stacked across the slope act as a barrier to water movement.

In a recent Ohio Beef Cattle Letter, Daniel Lima, Ohio State University Extension Educator in Belmont County, discussed the importance of a thatch layer forming on the outside of a round bale. The thatch layer forms from oxidation that takes place on the outer layer, especially with grasses. This layer helps to shed water and protect the inner layers.

Factors that increase the probability of an effective thatch layer forming include good bale uniformity and density, fine-stemmed grasses, leafy grasses, and the absence of weeds. Those things that contribute to a poor thatch layer forming include annual or coarse-stemmed grasses and weeds.

Actual forage dry matter and quality losses will depend largely on weather and length of storage. Those regions that receive less precipitation can drive a bit faster than those that receive more rainfall and snow. Nevertheless, if storing bales outside, a little bit of planning to preserve harvested yield and quality will pay big dividends over the long haul. If you choose to drive too fast, you'll pay for a hay barn without actually ever building one.