end of a driveway advertising straw and hay for sale. You can also approach a local feed mill, farmers’ co-op, or grain elevator. They will know who is growing grain and might be able to put you in contact with an appropriate source. They may be willing to broker the sale for you, although they will add a percentage to the cost for providing the service. Farmers’ markets, agricultural fairs, farm equipment sales centers, or any other places that farmers frequent can be good places to start. An advertisement in a few small town newspapers or wanted flyers can also put you in direct contact with farmers who have bales. As bale building grows in popularity, regional bale building associations are formed. These groups can put you in touch with good bale suppliers, as can bale home owners, designers, and builders. The Last Straw’s annual Resource Guide lists bale suppliers by state and province.
Old Bales, New Bales, No Bales
You can use bales that have been in storage from previous harvests, or you can preorder your bales from the current grain harvest. Remember that bales are an agricultural product and therefore are susceptible to fluctuations in weather, crop prices, and demand. There are both lean and abundant bale years. Where grain production is modest in scale, farmers will sometimes reserve their entire harvest for their own use. For this reason, it is best to source your bales as early as possible.
Round Bales Don’t Work
In recent years, baling machines that create large, round bales have come into favor with many farmers. However, you can’t build with round bales. You’ll have to specify that you need square bales. If contacted prior to harvest, some farmers who currently bale round might use their old square baler in order to make the sale to you. It can sometimes be frustrating to see literally tons of straw at hand but in a form you can’t use. Be persistent — somebody out there has square bales for you.
Plastered round bales may perhaps make for an interesting way to create structural columns, but nobody to our knowledge has tried this ... yet!
Two-string versus Three-string Bales
Much of the pioneering work in reviving straw bale construction was done in the southwestern United States. There, large three-string bales are common. In areas of small-scale grain farming, two-string bales are the norm. Both are suitable for building purposes; the kind you use will be determined by the baling standard in your local area.
The Three Bale Basics
When faced with a towering mound of hundreds or thousands of bales, it’s good to know what to look for. You have three basic concerns: tightness, dryness, and size. Before making your purchase, be sure you are satisfied on all three counts.
Tightness
You want your bales tight. Bales can be tied with polypropylene string, sisal twine, or metal wire. Any of these options is fine. It is the solidity of a straw bale that allows it to be used as a building material, and that solidity — or lack thereof — is a direct result of how tightly the bale has been tied. A farmer can adjust the baling machine to vary the tightness. Really tight bales use less twine or wire to bale an entire field but are heavier and harder to handle. If you are preordering your bales, be sure to specify that you want them on the tight side. But what exactly is tight?
Methods for assessing tightness vary from the low tech to the scientific. For the low-tech method, pick up the bale by its strings and check that they don’t lift from the bale by more than five to six inches. The bale should also maintain its integrity if you lift it by just one string and shake it around. If it spills out when you do this, the bales are too loose. Be sure you sample a number of bales from different places in the stack.
Some attempts have been made to more scientifically quantify tightness. The Arizona and California Straw Bale Codes specify that bales shall have a minimum calculated dry density of 7.0 pounds per cubic foot. This requires you to weigh, measure, and record the moisture content of the bales. If you are in serious doubt about the bale quality, these figures may be useful to generate. But don’t forget, the farmer has likely been around bales for a long time. He or she will understand the concept of a tight bale, and their opinion can mean as much or more than your calculations.
Dryness
Starting with dry bales is of utmost importance. Like any organic material, straw will decompose if the right conditions of moisture and temperature exist, and by ensuring that the moisture content is low, you remove one of the essential factors for decomposition.
Like methods for determining tightness, methods for determining moisture content vary in complexity. For the low-tech option, open the strings on several different bales and look inside. Is the straw moist to the touch? Is it crisp? Does it smell damp? Are there any hints of black mold on the straw? Study the storage facility. Is the roof good? How about the floor and walls? Ask the farmer about the weather conditions when the straw was baled. Was it a damp summer with lots of rain? Typically, if bales pass these tests, they are fine to use.
3.3: The strings of a bale shouldn’t lift more than 5 to 6-inches when you lift the bale. The bale should keep its shape and not bend or sag.
If you are buying bales from a previous year’s harvest, the survival of the bales without rot or mold occurring can tell you that they are adequately dry.
If you want to be more scientific, use a moisture meter to get an accurate reading of moisture content. The farmer may own a meter or may be able to borrow one from a neighbor or from a co-op. Moisture meters are most often used on hay bales but can give accurate readings for straw as well. Moisture content of 20 percent is considered the safe maximum for a building bale (this is the same figure for lumber). To calculate the dry density of a bale, subtract the weight of the moisture from the overall weight of the bale.
3.4: If you can find straw that is being stored in a well roofed barn, chances are it is nice and dry. Leave it in the barn until you actually need it.
Keep in mind that farmers don’t want wet bales either. Moist bales will mold in the barn and make for lousy bedding for the livestock. It is common farming practice to bale straw under good dry conditions, and to keep it dry once it has been baled.
Size
Size is the least important concern for building bales.As long as the bales are of consistent height and width, their exact dimensions are not so important. Two-string bales, as shown in Figure 3.5, are generally 14 inches high, 30 – 40 inches long and 18 – 20 inches wide. Three-string bales are 14 – 17 inches high, 32 – 48 inches long, and 23 – 24 inches wide. It doesn’t matter if your bales vary from these numbers, as long as they are consistent with each other so that your bale wall doesn’t vary greatly in height or width.
Other Factors to Consider
Before You Buy
Some general concerns about bales should be addressed.Many modern combines chop the straw into short pieces as it is harvested. This chopped straw can be baled into good tight and dry bales, but they are much more difficult to cut, shape, and trim. The
