Friday, January 11, 2013


As I discovered in Organic Transitions the FOOD WEB is the key to healthy soil.  To better understand soil is the key into the web.
 The following is taken from the NRCS
Healthy soil gives us clean air and water, bountiful crops and forests, productive grazing lands, diverse wildlife, and beautiful landscapes. Soil does all this by performing five essential functions:

  • Regulating water
  • Sustaining plant and animal life 
  • Filtering potential pollutants -
  • Cycling nutrients
  • Supporting structures

The Inherent and Dynamic Qualities of Soil 

Soil has both inherent and dynamic qualities.

Inherent soil quality is a soil’s natural ability to function. For example, sandy soil drains faster than clayey soil. Deep soil has more room for roots than soils with bedrock near the surface. These characteristics do not change easily.
Dynamic soil quality is how soil changes depending on how it is managed. Management choices affect the amount of soil organic matter, soil structure, soil depth, and water and nutrient holding capacity. Soils respond differently to management depending on the inherent properties of the soil and the surrounding landscape

Why focus on soil organic matter?

Many soil properties impact soil health, but organic matter deserves special attention.

  • It affects several critical soil functions
  • can be manipulated by land management practices
  • and is important in most agricultural settings across the country
Because organic matter enhances water and nutrient holding capacity and improves soil structure, managing for soil carbon can enhance productivity and environmental quality, and can reduce the severity and costs of natural phenomena, such as drought, flood, and disease. In addition, increasing soil organic matter levels can reduce atmospheric CO2 levels that contribute to climate change.
The soil food web glossary


Soil organic matter” includes all the organic substances in or on the soil. Here are terms used to describe different types of organic matter. See the "Components of Soil Organic Matter" chart below.

  • Living organisms: Bacteria, fungi, nematodes, protozoa, earthworms, arthropods, and living roots.
  • Dead plant material; organic material; detritus; surface residue: All these terms refer to plant, animal, or other organic substances that have recently been added to the soil and have only begun to show signs of decay. Detritivores are organisms that feed on such material.
  • Active fraction organic matter: Organic compounds that can be used as food by microorganisms. The active fraction changes more quickly than total organic matter in response to management changes.
  • Labile organic matter: Organic matter that is easily decomposed.
  • Root exudates: Soluble sugars, amino acids and other compounds secreted by roots.
  • Particulate organic matter (POM) or Light fraction (LF) organic matter: POM and LF have precise size and weight definitions. They are thought to represent the active fraction of organic matter which is more difficult to define. Because POM or LF is larger and lighter than other types of soil organic matter, they can be separated from soil by size (using a sieve) or by weight (using a centrifuge).
  • Lignin: A hard-to-degrade compound that is part of the fibers of older plants. Fungi can use the carbon ring structures in lignin as food.
  • Recalcitrant organic matter: Organic matter such as humus or lignin-containing material that few soil organisms can decompose.
  • Humus or humified organic matter: Complex organic compounds that remain after many organisms have used and transformed the original material. Humus is not readily decomposed because it is either physically protected inside of aggregates or chemically too complex to be used by most organisms. Humus is important in binding tiny soil aggregates, and improves water and nutrient holding capacity.
 Now that we have established soil Health let's look at the FOOD WEB. next installment

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