The ratio of organic carbon to organic matter in soil is typically around 0.54. This means that for every 1 gram of organic carbon in soil, there are about 1.85 grams of organic matter.

The factor of 1.724 is used to convert organic carbon to organic matter because it is the average value of the ratio of organic carbon to organic matter in soil. This factor can vary depending on the type of organic matter, soil type, and soil depth. For example, the factor of 1.724 is more accurate for mineral soils than for organic soils.

Dr Murtadha Shukur thank you for your contribution to the discussion

The organic matter is made of about aprox 55% C. If you are using Walkley Black, K2Cr7O7 react a total of 77% C. If you combine it you get 1.72 factor.

If you are using a high degree flame only use the 55%.

We are taught to determine soil organic matter; we first measure soil organic carbon (e.g. Walkley-Black method or CN analyzer) then multiply by the conversion factor of 1.72 or 1.724. The conversion factor is in common use despite many studies show that the 1.724 conversion factor is too low and for most soils the value of 2.0 is more appropriate (Pribyl, 2010).

See Art. below (Pribyl has a ResearchGate Page)

A critical review of the conventional SOC to SOM conversion factor

• May 2010
• Geoderma 156(3):75-83
• 10.1016/j.geoderma.2010.02.003
• Douglas W. Pribyl

Dr R B Brobst thank you for your contribution to the discussion