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2. Soil Fundamentals
There are a lot of names derived from Greek
and Latin in the following lists of microbe types.
Don’t let them hang you up. Pay attention
instead to what these organisms do and why
they are important for understanding soil health.
1.
Put a circle around groups that are
important in the nitrogen cycle.
2.
Put a square around groups that
are important in secondary or
micronutrients important to plants.
Underline groups that are important
in carbon cycling (photosynthesis and
decomposition).
Note: some groups may have more than
one function and some may not have a
direct connection.
Plant-associated
•
Rhizobia – bacteria that live inside roots,
in specialized structures called nodules;
some draw nitrogen from the air and fix
it in soil in forms usable by plants.
•
Mycorrhizae – root-associated fungi that
often play roles in plant uptake of water
and nutrients (for example, phosphorus).
Note: There tend to be more microorganisms
in areas of soil where roots are living than in
areas without living roots.
Activity – Functional Groups of Microbes
Activity – Functional Groups of Microbes
Free-living
•
Photosynthetic bacteria
•
Free-living nitrogen fixers – bacteria in
the soil that can fix nitrogen.
•
Denitrifying bacteria – soil bacteria
that convert solid nitrogen forms into
nitrogen gas.
•
Extremophiles – organisms able to live
in extreme environments, such as hot
springs, areas of highly saline water or
soil, and areas of extreme cold.
•
Anaerobic organisms – rely on chemicals
other than oxygen for their metabolism;
they are important in cycling nitrogen,
sulfur, iron, and manganese.
•
Saprotrophic microbes – consume dead
plant material above and belowground.
•
Predators – eat living organisms.
•
Scavengers – eat dead organisms.
Other
•
Parasites – live on other living
organisms and harm them by
consuming their tissues.
•
Disease-causing organisms – viruses,
bacteria, and other microbes that
may cause disease to plants or other
organisms.