If you have a farmstead forest, you most likely have a reliable supply of firewood. Whether you are selling firewood or burning it yourself in a fireplace, woodstove, shop heater or firepit in the backyard, how the wood burns and how much heat it supplies is a valid consideration.

If you are trying to clean up your woodlands from fallen limbs and using it in your shop heater, you probably don't care what species you cut up. But there are differences in species if you are going for the best heat value of the wood. And if you are marketing firewood, you need to understand how to add value through sorting, seasoning and deciding what kinds of "loads" you are going to sell.

John Ball, South Dakota State University Extension forestry specialist, fields lots of firewood-related questions each winter. "Not all firewood is the same," Ball says. "The different species vary in their heat value, color of the flame, fragrance and amount of sparks," which can all make a difference, depending on what you or your firewood customers are looking for.

"Crabapple and apple have one of the prettiest flames, while oaks and sugar maples have excellent coals," Ball explains. "Cottonwood goes to ash fairly quickly, and pines produce a lot of sparks." He notes that if you are looking for a pleasant fragrance, apple is one of the best. However, catalpa and elm, especially if it had a wetland disease, might have an offensive odor.

Bring on the heat
For firewood users and customers, heat value is a priority. Not all wood is created equal. Bur oak and mulberry top the heat value species list, providing 25 British thermal units per cord of wood, followed closely by honeylocust and sugar maple. Black walnut gives 22 Btu, with crabapple, green ash, hackberry and American elm following closely behind. In fact, Ball notes that a cord of green ash wood, highly coveted by many wood burning enthusiasts, has the heat equivalent of about 200 gallons of propane.

At the bottom of Ball's list are boxelder, providing 17 Btu per cord, with Ponderosa pine, aspen, cottonwood and basswood carrying up the rear.

"Oak is going to generate almost twice the heat as basswood or cottonwood, so customers would expect to pay more for this wood," Ball says.

With a cord being a stack of wood 4 feet wide, 4 feet high and 8 feet long, containing 128 cubic feet of packed wood and about 70 to 80 cubic feet of solid wood, most firewood can be priced by the cord. While you can find pickup loads of wood bringing $75, a cord might bring $150 or more. Why is this?

A cord is a known quantity, so although the pickup load sounds cheaper, it is only about one-fourth to one-third of a cord. A cord contains three to five times more wood than the pickup load, Ball says. You can add more value to firewood by "seasoning" the wood, that is splitting the wood and storing it off the ground, so it is protected from the elements for about a year. This seasoned wood will have a moisture content of less than 28%, so it should burn long and hot, rather than steaming and smoking in the fireplace. For those marketing wood, seasoning and sorting the wood so customers know what they are getting can be easy ways to add value to your product.

Finally, Ball notes concerns about emerald ash borer and the sale of green ash firewood across state lines. EAB has now been located in several states across the upper Great Plains and Midwest on into the East, so using and marketing firewood that stays local is the best way to curb spread of EAB to locations where it doesn't currently exist.

You can learn more by emailing Ball at [email protected].