To convert fraction organic carbon (OC) to soil organic matter (SOM), you can use a conversion factor called the soil organic matter factor (SOF). The SOF accounts for the non-carbon components of SOM, such as nitrogen, phosphorus, and other elements. The conversion formula is:

SOM = OC * SOF

The specific value of the SOF depends on the soil type, land management practices (e.g., land use, fertilizer application, tillage), and the region. The SOF can range from approximately 1.3 to 2.0.

Now, let's talk about the difference between soil organic carbon (SOC) and soil carbon. SOC refers exclusively to the carbon content in the soil's organic matter fraction, which includes decomposed plant and animal residues. On the other hand, soil carbon encompasses the total carbon content in the soil, including both organic carbon and inorganic carbon.

SOC is crucial because it acts as the primary reservoir for storing carbon in the soil. It plays a vital role in soil fertility, water holding capacity, nutrient cycling, and overall soil health. Monitoring SOC levels and promoting practices that increase SOC can help mitigate climate change by sequestering atmospheric carbon dioxide.

Soil carbon, on the other hand, encompasses both organic carbon and inorganic carbon. Inorganic carbon refers to carbonates present in the soil, primarily calcium carbonate (CaCO3) and magnesium carbonate (MgCO3). Inorganic carbon is not directly involved in the soil's organic processes and plays a minor role in soil fertility.

Understanding the difference between SOC and soil carbon is essential for accurately assessing soil health, carbon sequestration potential, and implementing effective soil management practices.

Dr Godwin Sabah thank you for your contribution to the discussion

We can estimate the percentage of SOM from the SOC% using the conversion factor 1.72 (derived from 100/58). This conversion factor can vary in different soils, but 1.72 provides a reasonable estimate of SOM for most purposes. Organic matter (%) = Total organic carbon (%) x 1.72. This conversion factor assumes organic matter contains 58 % organic carbon. However this can vary with the type of organic matter, soil type and soil depth.The conversion factor of 1.724, based on the assumption that organic matter is 58% carbon, has been used for converting measurements of soil organic carbon (OC) into estimates of soil organic matter (OM). Fraction of Organic Carbon in a soil, which is simply its Total Organic Carbon content expressed as a decimal fraction (e.g. 1.0% TOC = 0.010 Foc). Photosynthesis in land plants fixes atmospheric CO2 (inorganic carbon) as organic carbon, which is either stored as plant biomass or in soil, or is decomposed back to CO2 through plant and soil respiration. Total soil carbon includes both organic and inorganic carbon. Soil organic carbon includes the once-living matter from plants, dead leaves, roots, and soil microbes, while inorganic carbon is mineral-based and much less responsive to management. Total organic carbon (TOC) is the carbon (C) stored in soil organic matter (SOM). Organic carbon (OC) enters the soil through the decomposition of plant and animal residues, root exudates, living and dead microorganisms, and soil biota. While carbon is the primary component, soil organic matter also contains hydrogen and oxygen and is an important source of nutrients; nitrogen, phosphorus, sulphur and trace elements. Total carbon is the sum of three carbon forms; organic (described above), elemental (which is insignificant in most soils) and inorganic (usually carbonates and bicarbonates). The term total carbon is different to total organic carbon, which refers specifically to the organic carbon fraction.