@Colinhendee interesting topic. I wonder if a granular humate product would be better suited?

How would you apply the biochar? Banding it in furrow (assuming row-crops) is a good strategy. Some research with ‘raw’ biochar has actually shown yield decreases initially because biochar has a strong affinity for nutrients and can temporarily tie them up. Inoculating or ‘charging’ the biochar with nutrients and/or biology before application can alleviate this. Most broadcast applications of raw biochar in Iowa haven’t had much effect, mostly because we already have quite fertile soil with relatively high OM. It may be much more beneficial in your situation.

As you noted there is huge variation in biochars, which makes it very hard to predict what the effects will be. You do some expensive characterization of the biochar but even then it’s guesswork. My take is that any negative effects will be temporary and you can’t really go wrong with adding some biochar to low OM soil. It will almost certainly boost your CEC along with numerous other potential benefits.