“Substratum” means the part of the soil below the layer(s) of the soil profile in which the processes of soil formation are active.

Source. #9343, eff 1-1-09; ss by #12342, eff 8-15-17 (formerly Env-Wq 1502.58); ss by #14472, eff 1-19-26, EXPIRES: 1-19-36 (formerly Env-Wq 1502.65)