Not all firewood is created equal. Some species of trees are able to produce much more heat per cord of wood. A cord is the amount of wood in a well-stacked woodpile measuring 4 feet wide by 8 feet long by 4 feet high.
Following are heat values (in million BTUs) per cord for various species of trees. The higher the value, the better the wood.
Ash, Green - 22.8
Cottonwood - 15.9
Elm, American - 19.8 (Difficult to split)
Elm, Red - 20.6 (Difficult to split)
Elm, Siberian - 20.9 (Difficult to split)
Hackberry - 21.0
Honeylocust - 25.6
Locust, Black - 28.3 (Difficult to split)
Maple, Sugar - 24.0
Maple, Silver - 18.9
Mulberry - 25.3
Oak, Red - 24.0
Oak, Bur - 24.9
Oak, Post - 25.6
Osage Orange (Hedge) - 32.6 (Sparks, do not use in open fireplace)
Sycamore - 19.5 (Difficult to split)
Walnut, Black - 21.8
The Kansas Forest Service has a publication titled "Managing Your Woodland for Firewood" that is quite helpful. See http://www.ksre.ksu.edu/bookstore/pubs/mf773.pdf
Remember to obtain firewood locally. Emerald Ash Borer has spread in Kansas primarily because of transported wood.
Stacy Campbell is a Crop Production Extension agent in the Cottonwood District (which includes Barton and Ellis counties) for K-State Research and Extension. You can contact him by e-mail at [email protected] or by calling 785-628-9430.