Soil microorganisms – Microbz Soil

Microbz Soil

The basis of all life

Soil micro-organisms

The importance of soil organisms in healthy soils cannot be overlooked as they are accountable for the optimal performance of key soil functions. Soil organisms exist in large numbers in the soil as long as there is a carbon source for energy. Soil biodiversity comprises beneficial bacteria that spend their life inside and outside the soil. They range in size from microscopic cells that digest decaying organic matter to small mammals that play an important role in maintaining soil fertility. The average handful of soil contains billions of different living organisms and contains about 8 – 15 tons of bacteria, fungi, protozoa, nematodes, earthworms, and arthropods which all play an important role in maintaining soil health and fertility.

Relative number and biomass of microbial species at 0-6 inches depth of soil

Microorganisms Number/g of soil Biomass (g/m2)
Bacteria
10’8-10’9
40-500
Actinomycetes
10’7-10’8
40-500
Fungi
10’5-10’6
100-500
Algae
10’4-10’5
1-50
Protozoa
10’3-10’4
Varies
Nematodes
10’2-10’3
Varies

There is a large number of bacteria in the soil but because of their small size, they have a small biomass. Actinomycetes are 10 times smaller but are larger in size so they have a similar biomass to bacteria. Fungus population numbers are smaller, but they dominate most of the soil mass. Bacteria, actinomycetes and protozoa are robust and can tolerate more disturbances within the soil than fungal populations

The majority of a plant’s nutrients are derived from beneficial microbes in the soil surrounding the plant’s roots. In addition to this, soil organisms also:

  • Maintain nutrients in the soil
  • Compete with, inhibit and consume diseases
  • Decompose plant residue
  • Improve water infiltration and water holding capacity of the soil

Soil organisms are usually divided into five arbitrary groups:

Protists: includes bacteria, actinomycetes and algae
Microfauna: single-celled protozoans, small flatworms and nematodes.
Mesofauna: includes creatures that feed on microorganisms decaying matter and living plants
Macrofauna: this group includes slugs, snails and millipedes
Megafauna: makes up the largest soil organisms and include the largest earthworms

Earth worms are perhaps the most important creatures that reside within soil. They pass both soil and organic matter through their guts, in the process aerating the soil, breaking up the litter of organic matter on its surface and moving the material vertically from the surface to the subsoil. This develops the soil structure for plants and other organisms making it extremely important to soil fertility.

Another important role of soil organism is breaking up the complex matter from decomposing plants and animals so that they can be used again by the plants. This makes soil organisms a catalyst in a number of natural cycles.

Though soil organisms have become less important in agriculture due to the development of synthetic fertilisers, plants have thrived without human intervention for millions of years. And despite the reduction of using them within agriculture, they play a vital role in natural ecosystems such as the creation of humus, an organic material composed of decaying leaves and other vegetable matter. They also play a vital role in woodlands. To have healthy soil and crops, it’s important to re-establish a diversity of beneficial bacteria and limit the use of synthetic solutions.