mighty microbes
Nearly every living creature and organism on Earth relies on others
within its ecosystem to perform certain tasks and help fuel the natural progression of life. Think of it this way: a coyote hunts down
and kills a rabbit. After the coyote consumes its fill of flesh
and protein, it leaves the carcass behind and moves on.
Though the coyote has discarded what remains of
the dead rabbit, this is only the beginning of the
story. As the rabbit carcass sits, it will begin to
attract smaller animals and insects that will
continue to break down what remains,
including bones, tendons, vascular tissues
and proteins. This decomposition
food source for soil bacteria
continues all the way down to the
is fresh, young plant
smallest microscopic organisms in the
soil that consume the last of the deceased
material, or green matter,
rabbit’s organic matter and release the
which the bacteria can
remaining carbon and nutrients into the
easily break down.”
soil. Just as many animals, insects and soil
microbes have relied on the consumption of
the rabbit to obtain vital nutrients for survival,
plants rely on tiny soil microbes to further break
down organic matter, eventually improving soil
fertility by converting the organic matter into a form that
is readily available to the roots of a needy plant. The following is a
Bacteria
brief overview of two kinds of soil microbes that can directly affect
Bacteria are the most populous
the growth of a plant—bacteria and fungi.
micro-organisms found in
A favorite
healthy soils. These tiny,
single-celled creatures are microscopic in size and anywhere
from 300,000-500,000 of them can fit into a period at the end
of a sentence. Bacteria are the oldest, most primitive forms of
life and come in three styles or shapes: spiral, coccus (oval)
and bacillus (rod-shaped), all of which are active in the soil.
In nature, bacteria serve as one of the main decomposers
of organic matter, second only to fungi, making them a vital
part of the soil food web.
By decomposing dead plant and animal materials, the
bacteria in turn ingest organic carbon compounds, nitrogen and any other elemental nutrients present. The nutrients are then held or immobilized within the bacteria and
released when it dies. The process by which the nutrients
are converted and released in plant-accessible forms is
called mineralization. A favorite food source for soil bacteria is fresh, young plant material, or green matter, which
the bacteria can easily break down because of its high sugar
content. The older plant material (brown matter) contains
more complex organic carbon compounds that require
initial decomposition by other organisms before bacteria
can benefit. The green matter they consume contains
the carbohydrate cellulose, which is comprised of chains
of carbon-based glucose. Half of a plant’s mass is made
up of cellulose, so bacteria have a plentiful food source
when they colonize the soil near it. Another popular food
source for bacteria is root exudates—the compounds roots
excrete—and large numbers of them will populate a plant’s
rhizosphere, where they break down organic matter, such
as dead root cells, and help feed the plant.
124
Maximum Yield USA | January 2015