When asked “What is soil?”, Dr. Bob, Director of Plant and Soil Sciences at Holganix, LLC replied, “Soil is the source for all food and fiber consumed on Earth. It is a medium composed of minerals, organic matter, water, air and living organisms. It provides infrastructure to support and nurture plants.” Let’s take a brief look at each of these key components.
There are numerous different minerals, all charged with an important task to promote plant and soil health. Some of the key minerals include:
Carbon – The building block of all organic chemistry.
Calcium – In plants, calcium is a structural component of the cell wall. In plants, fungi and bacteria, calcium is a cofactor in regulating internal chemical processes. In soil, calcium shifts the pH to alkaline (vs acid).
Manganese – An essential element of chlorophyll (think Photosynthesis)
Nitrogen – All plant and animal proteins contain nitrogen. It is essential to life.
Potassium – An essential plant nutrient involved in the regulation of photosynthesis and water management in plants.
Phosphorous - an essential element in the biochemistry of photosynthesis, metabolism of sugars, energy management, cell division and the transfer of genetic material. In fact, phosphorous is essential to all life forms.
Sulfur – An important component of amino acids and proteins.
2. Organic Matter
3 to 5% of soil consists of organic matter. It is derived from dead and decaying plants and animals. It contributes to soil nitrogen, phosphorous and sulfur. The end result of organic matter is humus, which is created after microorganisms break down the organic matter.
Water acts as a solvent and carrier for plant nutrients. Just like all animals, microorganisms require water for their metabolic processes.
4. Soil Air/Atmosphere
50% of soil volume consists of pore spaces filled with air and/or water. Gases found in soil air include: oxygen, nitrogen, carbon dioxide and water vapor. However, due to respiration of soil microorganisms, soil air has more carbon dioxide than the air we breathe (the atmosphere above the soil).
5. Soil Microorganisms
There are more microbes in 1/3 cup of soil, than there are people on earth! Soil microorganisms include: bacteria, fungi, algae, protozoa, arthropods, nematodes and worms. Often, tilled soil (soil used in agriculture and landscaping) is more bacterially dominant while non-tilled soil (soil found in a forest) is more fugally dominant.
Want to learn more? Click the movie below to watch Dr. Bob’s webinar entitled Digging into the soil food web.