Back to Biochar. So I am reading the book (cherry picked really, I got about ½ way through, I’ll pick the other ½ and analyze it at a later date. Fortunately, I have a short attention span, ADD and dyslexia) The first part was about the history of biochar’s invention/use in the Amazon and how it made the soil extra fertile in the form of Terra Preta or “black earth”, even to this day. Then I found what I was looking for. According to the book, there are two types of carbon that are important, labile and recalcitrant. It turns out that biochar is of the recalcitrant type of carbon.