ISO/WD 21251

Guidance for estimating organic carbon stocks in soils according to their biogeochemical stability or residence time

Scope

This standard specifies general requirements for assessment of organic carbon stocks in soils based on their
biogeochemical stability or residence time. It allows assessment of carbon sequestration as well as determination of carbon sequestration potential.

It establishes an exhaustive list of methods currently allowing estimation of the content of organic carbon
pools according to their stability and residence time.

○ Densito-granulometry fractionation
○ Thermogravimetry
○ Differential scanning calorimetry
○ Rock-Eval
○ TOC400
○ KMnO4
○ In situ basal respiration - field tests
○ Laboratory basal respiration
○ Quantification of amino sugars

The methods that allow quantifying total organic carbon content, without differentiation of stability or
residence time of organic carbon pools are not within the scope of this document. (e.g. elemental analysis).
This standard is applicable to a wide range of soils:

○ Agricultural soils
○ Forest soils
○ Pastures and meadows
○ Peatlands and wet grasslands
○ Permafrost
○ Urban soils
○ Technosoils
○ Organic amendments (biochar, compost, digestate, etc…)