Soil organic matter has a strong relation to total organic carbon. and about 85% of organic carbon consists of humic substances (HS). classified as humin (HU). humic (HA) and fulvic acids (FA). https://www.diegojavierfares.com/amazing-price-Kicker-48CDF104-Comp-10-Down-Firing-Loaded-Subwoofer-Enclosure-special-find/