the main rooting zone. By far, most soils are sampled to a depth of
0.3 m or less, and samplings below 1 m are an exception (Fig. 1). The
recommended sampling depth varies between soil types and biomes. It
has been shown that the SOC pool in the upper mineral soil is not a useful
estimator of the total soil C pool as a substantial fraction of this pool can be
stored in the subsoil. This has been shown for editerranean, temperate,
boreal, and arctic ecosystems