Calculate concentration of soil organic matter in content gi

Calculate concentration of soil organic matter in content given the concentration of organic carbon

SOC- 17kg-1 to SOM=?

Solution

In the Soil to Ground Water Partition Model, the coefficient, Kd, for organic compounds is the Foc multiplied by the chemical-specific soil organic carbon water partition coefficient, Koc. Therefore for organic compounds,
Kd = Foc x Koc
Typical Indiana surface soils have soil organic matter (SOM) contents in the 1 – 6% range, depending upon soil type. Since organic carbon is thought to comprise about 58% of the SOM, the upper range of Foc for fertile surface soil is expected to be less than approximately: 6% SOM * 0.58 = 3.42% (0.0342 g/g) organic carbon. Subsurface soils are expected to be much lower in organic matter. The EPA’s Soil Screening Guidance recommends 0.2% (0.002 g/g) as the default concentration of organic carbon for subsurface soils. Foc concentrations above the RISC default concentration of 0.2% (0.002 g/g) will necessitate an explanation of the source of the organic carbon being reported.