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30 Cards in this Set
- Front
- Back
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What are the 3 GENERAL factors for CLASSIFICATION in soil biology?
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- Basic type, functional groups, & size
- Energy source & carbon source - Environmental tolerance |
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What are the BASIC TYPES (3 domains + 5 kingdoms), FUNCTIONAL GROUPS, and SIZES used in the classification of soil organisms?
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Domains = Archaea, Bacteria, Eukarya
Kingdoms = Monera, Protista, Fungi, Plants, Animals Herbivores, Detritivores, Fungivores Micro-, Meso-, Macro- |
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what are the ENERGY/CARBON SOURCES used in the classification of soil organisms?
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Photo- & Chemo-
Autotrophic & Heterotrophic |
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What are the ENVIRONMENTAL TOLERANCES used in the classification of soil organisms?
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Aerobes, anaerobes, thermophiles, cold tolerant, salt tolerant, pH, extremophiles, etc.
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What are the 5 main GROUPS of soil organisms?
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Macroflora & Microflora,
Macrofauna, Mesofauna, & Microfauna |
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How MANY microflora ("microbes"), microfauna, and meso-/macrofauna are in 1 cup of soil?
(2 organisms each) |
Microflora:
Bacteria = 200 billion Fungi = 100,000 meters Microfauna: Protozoa = 20 million Nematodes = 100,000 Meso-/Macrofauna: Arthropods = 50,000 Earthworms = <1 |
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Define: Rhizosphere
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Zone of soil less than 2 or 3 mm from the root surface
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What is the percent of LIVING organisms in a soil's total OM?
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~1 to 8% by dry weight
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What are the main functions of MICROFLORA?
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**Stabilize soil aggregates
*Primary decomposers |
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What are the main functions of FUNGI?
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**Decomposition of cellulose (mainly in acidic FOREST soils)
*Improve soil structure using HYPHAE |
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Aggregates are held together by what 3 things?
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1. Fungal hyphae
2. Bacterial "glues" 3. Organic matter |
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Most plants have a symbiotic relationship with WHICH soil fungi?
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Mycorrhizae
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What are the two TYPES of mycorrhizae and their functions?
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"Endo" type:
works through into plant roots. Transfers nutrients (N, P, and K) in to the plant while the plant provides C for fungus. "Ecto" type: spreads through soil collecting and transferring nutrients. |
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What are the 4 methods for nutrient uptake in roots?
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- Mass flow
- Diffusion - Interception - Commensalism, mutualism, symbiosis, etc. |
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Define: Actinomycetes
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- Fungus-like filamentous bacteria
- Huge numbers in soil, second only to "regular" bacteria |
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What soil organism is responsible for the "good smell" after a rain storm, and why??
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Actinomycetes -- they sporulate during the rains so their spores are carried by water.
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What benefit do actinomycetes provide to humans?
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They produce antibiotic compounds that can be used for pharmaceutical purposes.
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What are the 3 terms used for BACTERIA and N- FIXATION???
(give an example for each) |
Free-living (aka- asymbiotic) ~ cyanobacteria
Associative ~ lichens = cyanobcteria + fungi Symbiotic (aka- nodule forming) ~ Legume + rhizobia |
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Up to 30% of all mineralized N- comes from WHAT?
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Protozoa (microfauna)
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Worms increase availability of mineral nutrients to plants by.......(2 things)
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1. Physical/chemical breakdown of organic materials
2. Bioaccumulation: collect, concentrate, and assimilate nutrients into their body tissue |
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In _____ soils, there is more biodiversity, and often dominated by fungi.
There is more faunal biomass in ______ soils. _____ soils are the least diverse with less biomass and fewer organisms. |
Forest soils...
Grassland soils... Cultivated soils... |
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What are 6 functions of soil microbes?
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- Aggregate stability
- Disease suppression - Cause of disease - Nutrient cycling - N- capture and fixation - Decomp. of organic matter |
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95% of all N- in the soils is unavailable because it is in WHAT?
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Organic compounds (i.e. proteins)
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What is the process in which organic N becomes available as a nutrient for organisms?
What about the other way? |
Mineralization
The opposite direction is Immobilization |
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What combination of symbiotic microfauna and plants has the fastest growth rate???
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Non-legume (grass) + fungi and legume + bacteria
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What is Soil Organic Matter???
Also, what are the 3 BIO-POLYMERS? |
Living and "once-living" substances
Biomass (living organisms), Detritus (dead tissue/waste), and Humus (non-living, non-tissue) |
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Rate of decomposition depends on what 4 factors?
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- Physical/chemical nature of the litter
- Temp. and moist. of the soil environment - Aeration (vs. anaerobic) - Kinds/numbers of soil fauna |
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What are the FIRST and LAST organic compounds to break down in decomposition?
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Sugar (glucose)
Lignin |
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Why is cellulose EASIER to decompose than lignin?
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One is a polymer of simple, repeating Glucose monomers.
The other is a complex structure with many different bonds and compounds. |
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What is the C:N threshold for nitrogen mineralization/immobilization???
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25:1
GREATER than is immobilization, LESS than is mineralization. |
