$$ \text{Organic Matter (%)} = \frac{M
The sample is held at this temperature for a specified period (often a minimum of 6 hours or until constant mass is achieved). At this temperature, the organic matter (carbon, hydrogen, oxygen, nitrogen, etc.) oxidizes and turns into gas, leaving the mineral content behind. Astm D 4073 Pdf
The process begins with a representative soil sample. The sample must be air-dried and pulverized to pass through a specific sieve (usually a No. 10 or 2.00 mm sieve). It is crucial to remove any large roots, sticks, or non-soil debris unless they are considered part of the soil mass. $$ \text{Organic Matter (%)} = \frac{M The sample