Factors Influencing Biochar Elemental Composition.

Feedstock choice, pyrolysis temperature and type (fast or slow) may be varied to optimize the desired biochar product.  In general, increasing pyrolysis temperature tends to decrease biochar yield, but increase biochar total C, K, and Mg content, pH (ash content), and surface area, and decrease cation exchange capacity (CEC).  Slow pyrolysis, in general, causes biochars to have greater N, S, available P, Ca, Mg, surface area, and CEC as compared to biochars produced using fast pyrolysis.  This presentation focuses attention on various biochars and the effects pyrolysis temperatures and types have on inherent biochar nutrients (total and available), pH, potential liming value, cation exchange capacity, and nutrient sorption and entrapment.  The laboratory methods utilized for characteristic determination will also be presented.