This system forms even more microzones that finalize the decomposition process and vigorously pursues the essential mineralization process. The essential plant nutrients are converted and released to the growing crop. Microbes are fixing nitrogen from the atmosphere. Nitrification microbes oxidize nitrogen within the soil. Microbes decompose cellulose.
Microbes decompose humates.
These are but the major biological functions occurring among many in this system. The first system occurs in all types of soils. Acidic soils have a strongly developed second system, a very weak third system, and no fourth system. It is the second and third systems that provide a continuous supply of nutrients to growing crops and truly represent a soil's natural fertility. Among the inorganic sorbents, clay minerals are the most important as they contribute to the germination and the activities of the soil microbes by enlarging the active surface of the substratum.