FEATURESTORY
by Bill Baugh
What Soil
Organisms
Actually Do
S
oils are teaming with life, from the micro-
scopic (bacteria) to the macroscopic (earth-
worms). In this article, we’ll examine some of
the common soil organisms and discuss what
they do in the soil.
Here’s a list of common organisms found in the
soil. Soils that do not have an abundant amount of
soil organisms tend to have soil problems. Keep in
mind that the soil ecosystem is extremely varied and
small changes in common soil characteristics (pH,
water, temperature, nutrient levels) can have a large
impact on the species found in the soil.
Bacteria
There are both aerobic and anaerobic in soil and
there can be as many as 100,000,000 bacteria per tea-
spoon of soil.
Fungi
These can be single celled and multi-celled and
there can be several yards per teaspoon.
Protozoa
One celled animals, and there are several thou-
sand protozoa per teaspoons of soil.
Nematodes
They are also called roundworms, with 10-20
nematodes per teaspoon of soil being normal.
Arthropods
This group includes insects and spiders with the
normal population being several hundred per cubic
foot.
Earthworms
One inch or more long and healthy soils will
have 5-30 earthworms per cubic foot.
As you can see, healthy soils contain a wide vari-
ety of organisms in the soil. From simple single celled
organisms, to more complex organisms like insects
and earthworms.
March 2019
The Value of Soil Organisms
From a farming perspective, a diverse and active
population of soil organisms has four main benefits;
nutrient cycling, enhancing soil structure, enhancing
plant growth and controlling plant disease. Each of
these benefits could be a topic on their own.
Nutrient Cycling
Probably the most important from a farming
perspective, soil organisms, particularly soil micro-
organisms, help store nutrients in the soil and create
new organic nutrients. Soil organisms are continually
transforming and recycling nutrients. The key tasks
of decomposition, mineralization, immobilization and
mineral transformation are all performed by soil or-
ganisms.
Enhanced Soil Structure
Crumbly, well aerated soils tend to support the
most crops. Soil organisms are the key component
of soil structure.
Enhanced Plant Growth
Beneficial soil bacteria and beneficial soil fungi
produce a wide variety of plant hormones. These hor-
mones stimulate plant roots.
Controlling Plant Disease
Soil organisms have a wide variety of ways to
deal with plant predators. Some of the microscopic
organisms complete with pathogens for food sources.
Insects and protozoa tend to consume some of the
harmful plant organisms, keeping their populations
in check.
Each type of soil organism fits a unique niche,
playing a different role in nutrient cycling, enhanced
soil structure, and controlling plant diseases and
plant predators. GG
Bill Baugh is a product manager for Custom Biologicals, Inc. a
manufacturer and distributor of innovative microbial products.
You can visit their website at Living-Soils.com and he can be
contacted at 561.797.3008 or [email protected].
www.GardenandGreenhouse.net
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