Microbes / Soil
Soil microbes/microorganisms (a wide ranging word to refer to a range of microscopic life, such as algae, bacteria and fungi), exist in large numbers in the soil as long as there is a carbon source for energy. Soils contain about 8-15 tons per acre of bacteria, fungi, protozoa, nematodes, earthworms, and arthropods, all important for the development of healthy soil structure. These microorganisms play an essential role in decomposing organic plant matter, cycling nutrients and fertilising the soil. There are more microbes in a teaspoon of soil than people on the earth.
Large amounts of bacteria exist in soil for a purpose. Due to its small size, it has a smaller biomass. Actinomycetes (formerly known as fungi), 10 times smaller in number than bacteria, but dominates the soil biomass when soil is not disturbed. Bacteria, actinomycetes, and protozoa (single or group comprising single-celled microscopic organisms) are hardy and can tolerate more soil disturbance than fungal populations, so they dominate in tilled soils (such as for farming), while fungal and nematode populations tend to dominate in untilled or no-till soils.
Organic plant matter decomposition serves two functions for the microorganisms, providing energy for growth and supplying carbon for the formation of new cells. Take a minute to let that digest – ORGANIC PLANT MATTER PROVIDES ENERGY FOR GROWTH AND AIDS FORMATION OF NEW CELLS. One could say HEALTHY CELLS and we know healthy cells equals a healthy body.
Soil organic matter (SOM) is composed of “living” (microorganisms). “Dead SOM” (fresh residues), and the “very dead SOM” (humus) fractions are organic and buried over 50 feet below soil and above carbon. The “very dead” or humus is the long-term (thousands of years old), soil organic matter fraction that is resistant to decomposition.
Soil organic matter has two components called the active (35 percent) and the passive (65 percent). Active soil organic matter is composed of the “living” and “dead” fresh plant or animal material which is food for microbes and is composed of easily digested sugars and proteins. The passive soil organic matter is resistant to decomposition by microbes and is higher in lignin.
Microbes need regular supplies of active soil organic matter in the soil to survive in the soil. Long-term no-tilled soils have significantly greater levels of microbes, more active carbon, more soil organic matter, and more stored carbon than conventional tilled soils.
Dead plant residues and plant nutrients become food for the microbes in the soil. Soil organic matter is basically all the organic substances (anything with carbon) in the soil, both living and dead. Soil organic matter includes plants, blue green algae, microorganisms (bacteria, fungi, protozoa, nematodes, beetles, springtails, etc.) and the fresh and decomposing organic matter from plants, animals, and microorganisms.