Question

how nutrients are represented in soil

Answer 1

Soil organisms are responsible, to a varying degree depending on the system, for performing vital functions in the soil. Soil organisms make up the diversity of life in the soil .
This soil biodiversity is an important but poorly understood component of terrestrial ecosystems. Soil biodiversity is comprised of the organisms that spend all or a portion of their life cycles within the soil or on its immediate surface (including surface litter and decaying logs) .

Soil organisms represent a large fraction of global terrestrial biodiversity. They carry out a range of processes important for soil health and fertility in soils of both natural ecosystems and agricultural systems. This annex provides brief descriptions of organisms that are commonly found in the soil and their main biological and ecological attributes.

Answer 2

Nutrients are replenished by certain different microorganism that are found in the soil or also by the death of certain plants such as the rhizobium plant. The decaying plants tend to slowly break down into the basic soil nutrients over a period of time.