Mineral surfaces and soil organic matter

Summary The organic carbon content of soil is positively related to the specific surface area (SSA), but large amounts of organic matter in soil result in reduced SSA as determined by applying the Brunauer–Emmett–Teller (BET) equation to the adsorption of N 2 . To elucidate some of the controlling mechanisms of this relation, we determined the SSA and the enthalpy of N 2 adsorption of separates with a density > 1.6 g cm −3 from 196 mineral horizons of forest soils before and after removal of organic matter with NaOCl. Likewise, we investigated these characteristics before and after sorption of increasing amounts of organic matter to four mineral soil samples, oxides (amorphous Al(OH) 3 , gibbsite,…