Geoscience Reference
In-Depth Information
Fig. 5.12
The scheme of the humifi cation process in the soil. The release of CO
2
accompanies
decomposition and mineralization. It is presented as the
broken line
degraded by bacteria. The products of decomposition are accompanied by newly
created organic molecules that appear in organic fi lms covering soil particles, which
are predominantly clay minerals. These new organo-mineral components of soil
change the physics and physical chemistry of soils (Fig.
5.12
).
Earthworms, digesting these and other organic nutrients together with clay min-
erals, contribute to the continual mixing of humifi cation products. They, together
with ants, are the primary actors drawing crude remnants of plants from the surface
down into the topsoil.
Individual components of organic matter are not decomposed and transformed at
the same rate. Organic acids, starch, glucose, lactose, and fructose are decomposed
quickly, while proteins and fats are decomposed slowly. Lignin, wax, and resin are
very resistant. Some organic compounds are partially incorporated into soil together
