The low temperature ignition of soil organic matter has been investigated for temperatures ranging from 100 to 500° C.

Appreciable losses are found to occur below 100° C.; up to 200° C. heating results essentially in the distillation of volatile constituents, while between this temperature and 300° C. destructive distillation is the major reaction. These reactions are responsible for the removal of 85% of the soil organic matter.

By 300° C. the greater part of the residual organic matter consists of carbonaceous material, and the final reaction is simple ignition of this material.

Two hours’ heating of the soil at 450° C. or about half an hour at 500° C. are recommended for the removal of 99% of the soil organic matter.