FEATURESTORY
by Eric Lancaster
How Pesticides Affect Soil Microbes
T
here is a symbiotic relationship between
microbes and plant life in a natural soil en-
vironment. Plants like grass, trees and food
crops depend on microorganisms in the soil
to obtain water, ward off dangerous organisms, pre-
vent nutrient loss and break down compounds that
could inhibit growth. Soil microbes, in return, benefit
from the health of plants growing in the soil. This
relationship creates a dynamic living system that is
easily broken by human systems that use pesticides,
herbicides and fertilizers. The chemicals humans use
to enhance plant growth can actually destroy the soil
system, killing or causing mutation pressure on the
soil microbes that all other organisms in the ecosys-
tem need to survive.
What Soil Microbes Do for the Ecosystem
A small handful of healthy soil will include bil-
lions of microscopic organisms including fungi,
nematodes, protozoa, micro-arthropods and other
beneficial bacteria. These microbes decompose or-
ganic material while they absorb water and nutrients
that would otherwise get lost in the soil; the ab-
sorbed water and nutrients is then used by more and
more complex creatures. This ecosystem ranges from
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the tiniest bacteria to the largest mammal predators.
Any damage suffered by one part of the system can
affect the health of all the others.
Three Levels of the Soil Ecosystem
The first level of the soil ecosystem consists of
bacteria and fungi that consume leftover organic mat-
ter, nitrogen and nutrients. These organisms act like
a nutrient bank that plants can use when they need
it. The second level of organisms consists of preda-
tors that feed on the bacteria and fungi. Nitrogen
and nutrients are metabolized and released into the
soil at a slow rate that is beneficial to plant growth.
Higher-level predators, like millipedes and earth-
worms, make up the third level. These animals keep
the second-level organisms in check, helping the
plants maintain a healthy growth rate. The third level
is also made up of bigger predators that keep the
smaller ones from over eating. This extensive bio-
diversity is what makes all life in the soil ecosystem
possible.
How Pesticides Affect Soil Microbes
Pesticides include a large group of chemical
agents that attempt to eliminate destructive biological
www.GardenandGreenhouse.net
June 2018