while a small proportion of the original carbon is retained in the soil through the formation of humus, a product that often gives carbon-rich soils their characteristic dark color (Fig.

producing an acid humus. The acidic conditions are not liked by soil organisms which would normally merge the boundaries of the horizons.

Humus is a rich dark organic material that is created ... This layer is dark in colour because of the large amount of ash present in the soil. The deposition is attributed to cultural formation ...

Soil organisms, like earthworms ... resulting in a layer of decaying leaves giving a rich humus. The deep roots of these trees reached down to the 'B' horizon, unlike with coniferous trees ...