Biological Properties

Microorganisms

Microorganisms are very small forms of life that can sometimes live as single cells, although many also form colonies of cells. A microscope is usually needed to see individual cells of these organisms.

Macro Fauna

While the most well‐known nematodes are pests occupying and feeding on plant roots (such as the lesion nematode and the soybean cyst nematode), in fact most nematodes are beneficial organisms. Nematodes are extremely important because they consume a diverse array of food sources, which places them at multiple trophic levels in the soil food web.

Particulate Organic Matter

Particulate organic matter (POM) fraction referred to in this document comprises all soil organic matter (SOM) particles less than 2 mm and greater than 0.053 mm in size (Cambardella and Elliot, 1992). POM is biologically and chemically active and is part of the labile (easily decomposable) pool of soil organic matter (SOM).

Total Organic Carbon

Total organic carbon (TOC) is the carbon (C) stored in soil organic matter (SOM). Organic carbon (OC) enters the soil through the decomposition of plant and animal residues, root exudates, living and dead microorganisms, and soil biota.

Soil Enzymes

Soil enzymes increase the reaction rate at which plant residues decompose and release plant available nutrients. The substance acted upon by a soil enzyme is called the substrate.

Soil Respiration

Carbon dioxide (CO2) release from the soil surface is referred to as soil respiration. This CO2 results from several sources, including aerobic microbial decomposition of soil organic matter (SOM) to obtain energy for their growth and functioning (microbial respiration), plant root and faunal respiration, and eventually from the dissolution of carbonates in soil solution.

Registration Open for 2026 Soil Health Conference!

The 2026 Soil Health Conference will be held Jan. 13-14 in Aberdeen, SD. Don't miss this outstanding opportunity to learn more about soil health land management practices! In addition to the keynote speakers, this conference will feature breakout sessions, discussion panels, award presentations, demonstrations, vendor booths, student contests, and more! This is a chance to network with experienced sustainable agriculture producers and experts and brainstorm solutions for your land management challenges!