scope:

This document presents a method to quantify the soil organic carbon and nitrogen stocks in mineral soils at plot scale. It also provides guidance on how to detect and quantify simultaneously the variations of carbon and nitrogen stocks over time in mineral soils at field scale. It is based on several documents already published[2],[3],[4],[5],[6],[7],[8]. This document does not apply to organic soils, soils with permafrost, wetland soils, or to soil layers prone to submergence below the groundwater table. NOTE 1   The possibility of increasing soil C storage is viewed as a means to sequester atmospheric carbon dioxide (CO2) and mitigate greenhouse gas (GHG) emissions. Information on soil nitrogen (N) stocks is crucial because it interacts with carbon cycling through plant nutrition and organic matter decomposition, and leakage of N is of environmental concern (e.g. N2O emissions, NO3- leaching). Therefore, it is becoming increasingly important to measure accurately the impact of changes of land uses and practices on organic carbon and nitrogen stocks. NOTE 2   While understanding changes in soil inorganic carbon it is important also to understand the land-atmosphere exchange of CO2, measuring stocks of soil inorganic carbon is outside the scope of this document.