Transcript LIFE in the soil

SOIL BIOLOGY
LIFE IN THE SOIL
SOIL BIOLOGY
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There are a DIVERSITY of ORGANISMS in SOIL
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SIZE
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What they EAT or PRODUCE
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MICROORGANISMS
MACROORGANISMS
PRODUCERS
HERBIVORES
PREDATORS
PARASITES
DECOMPOSERS
PREFERRED ENVIRONMENT
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AEROBIC – O2
ANAEROBIC – without O2
SOIL BIOLOGY
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CYCLES
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Focus on NUTRIENT CYCLING and the PROCESS
SOIL BIOLOGY
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WEBS
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Focus on ORGANISMS within the WEB
SOIL BIOLOGY
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WEBS
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COMPLEX
SOIL BIOLOGY
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SOIL ORGANIC MATTER - FOOD for the WEB
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ORGANIC MATTER is the portion of soil that contains PLANT and
ANIMAL RESIDUES at various levels of DECAY
SOIL BIOLOGY
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Most OM is made of
CHEMICALLY COMPLEX C
Compounds
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CARBOHYDRATES – long
chains of simple sugars
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SUGARS
STARCHES
CELLULOSE – primary cell
walls of live cells
LIGNIN - secondary cell walls
that make cells rigid, dead cells
PROTEINS – long chains of N
containing compounds (amino
acids)
SOIL BIOLOGY
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ORGANIC MATTER
DECOMPOSITION
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ACTIVE OM - OM easily
DECOMPOSED by MICROBES
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ORGANIC COMPOUNDS leaked from roots
Sloughed off ROOT PARTS
DEAD OM
MICROBES use RESPIRATION to break
down OM
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OM + O2 →→→→ CO2 + H2O + HUMUS
(respiration)
Occurs RAPIDLY – weeks to months
SOIL BIOLOGY
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HUMUS – OM that RESISTS
DECAY
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HUMUS is DARK and made of
tiny, CLAY sized particles
OXIDATION – chemical
decomposition of HUMUS
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HUMUS + O2 →→→→ CO2 + H2O
(oxidation)
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Occurs SLOWLY - 1-3% loss of
HUMUS / year
SOIL BIOLOGY
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NUTRIENT CYCLING of OM
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PLANTS can only use NUTRIENTS in simple INORGANIC IONS
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When NUTRIENTS are TIED UP in the BODIES of living
ORGANISMS or in FRESH OM they cannot be used by plants
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This is called IMMOBILIZATION
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Keeps NUTRIENTS from LEACHING
When MICROBES break down COMPLEX ORGANIC FORMS to
SIMPLER INORGANIC FORMS that PLANTS CAN USE
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This is called MINERALIZATION
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When MICROBES EXCRETE, DIE, or are EATEN by another ORGANISM
they will RELEASE NUTRIENTS that plants can use
SOIL BIOLOGY
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DISTRIBUTION of
SOIL BIOLOGY
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Top 2’ of SOIL – O and A
Horizons
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Most O2
Most H2O
Most OM
Best SOIL STRUCTURE
RHIZOSPHERE
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Where LEAKING and
SLOUGHING occurs
BACTERIAL dominated
SOIL BIOLOGY
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DISTRIBUTION of
SOIL BIOLOGY
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LITTER LAYER and in
HUMUS
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FUNGAL dominated where
COMPLEX C compounds
SOIL PORES
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Protozoa and Nematodes in
water films
Arthropods, Earthworms in
air spaces
SOIL BIOLOGY
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SOIL ORGANISM ACTIVITY
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DEPENDS on MOISTURE and TEMP
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As MOISTURE & TEMPERATURE increases, ACTIVITY increases
SOME ORGANISM is always ACTIVE
SOIL BIOLOGY - MICROORGANISMS
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BACTERIA
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MOST ABUNDANT
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SINGLE CELLED MICROSCOPIC organisms
RHIZOSPHERE
4 MAJOR
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DECOMPOSERS – consume SIMPLE C compounds
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SAPROPHYTIC
MUTUALISTS – N FIXERS
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BENEFICIAL relationship with PLANTS
Reside in ROOT NODULES
Take atmospheric N2 and convert to NH4+
PLANTS get NH4+ and BACTERIA get simple sugars
SOIL BIOLOGY - MICROORGANISMS
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BACTERIA
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4 MAJOR
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PATHOGENS - FEED on plant ROOTS
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CHEMOTROPHS (or LITHOTROPHS)
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FEED on INORGANIC COMPOUNDS
of N, S, Fe, or H
Important to N CYCLE
Some good at DEGRADING
POLLUTANTS
SOIL BIOLOGY - MICROORGANISMS
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BACTERIA
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2 ODD BALLS
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PHOTOSYNTHETIC CYANOBACTERIA
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PRODUCERS
Increase OM in soils
Live in WATER FILMS
ACTINOMYCETES
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FILAMENTOUS bacteria
Give soil EARTHY SMELL (geosmins)
DEGRADE COMPLEX C compounds
PRODUCE ANTIBIOTICS that can inhibit growth
Tolerant of DRY, HIGH TEMP and HIGH pH soils
Most are SAPROPHYTIC, some PARASITIC
SOIL BIOLOGY - MICROORGANISMS
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BACTERIA
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IMPORTANT ROLES of BACTERIA
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IMMOBILIZATION / MINERALIZATION of NUTRIENTS
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Produce GUMS that BIND soil particles
and BUILD SOIL STRUCTURE
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Some FILTER and DEGRADE POLLUTANTS
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DOMINANT in NEUTRAL pH soils and GRASSLANDS
SOIL BIOLOGY - MICROORGANISMS
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FUNGI
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FEWER numbers of FUNGI in soil,
but makes up the LARGEST MASS
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FILAMENTOUS,
MULTI-CELLULAR organisms
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HYPHAE
MYCELIUM
4 TYPES
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DECOMPOSERS – SAPROPHYTIC
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COMPLEX C compounds
Excrete organic ACIDS which increase
HUMUS
SOIL BIOLOGY - MICROORGANISMS
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4 TYPES
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MUTUALISTS - MYCORRHIZAE (fungus – root)
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ECTOmycorrhizae
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ENDOmycorrhizae – AM (VAM)
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Grows INTO CELLS of roots and forms ARBUSCLES (nutrient transfer),
VESCICLES (storage)
Cannot be artificially grown
ECENDOmycorrhizae (minor type)
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Forms a MANTLE surrounding ROOT and IN BETWEEN CELLS
Artificially grown and INOCULATED
Intermediate type seen in nurseries and after forest fires
Thin mantle and some cell penetration, but turns into ECTO as matures
Increases ABSORPTION of P, Zn, Cu, H2O
Some PROTECT PLANT from diseases causing PATHOGENS
SOIL BIOLOGY - MICROORGANISMS
SOIL BIOLOGY - MICROORGANISMS
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FUNGI
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4 TYPES
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PATHOGENS - DISEASE
causing organisms
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PREDATORS
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NEMATODE eating fungi
SOIL BIOLOGY - MICROORGANISMS
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FUNGI
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IMPORTANT CHARACTERISTICS
of FUNGI
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O Horizon for COMPLEX C compounds
AEROBIC soils
DOMINATE ACID soils, FOREST soils
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DETRIMENTAL HABITATS
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TILLAGE
FUNGICIDE use
High N or P FERTILIZER use
Fallowed FIELDS
Non-Mycorrhizae CROPS
SOIL BIOLOGY - MICROORGANISMS
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PROTOZOA
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SINGLE CELLED organisms
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3 TYPES
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CILIATES
AMOEBA
FLAGELLATES
FEED on BACTERIA
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C : N ratio BACTERIA, 4 - 5: 1
C : N ratio PROTOZOA , 10 : 1
As feed on bacteria EXCRETE
excess N as NH4+ (mineralization)
SOIL BIOLOGY - MACROORGANISMS
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NEMATODES
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Non – segmented, EEL-LIKE WORMS, 1/20” long
MULTI-CELLULAR organisms
PRODUCE EGGS in masses
SOIL BIOLOGY - MACROORGANISMS
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NEMATODES
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5 TYPES – based on what they
FEED on
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BACTERIAL feeders
FUNGAL feeders
PREDATORS
OMNIVORES
PLANT ROOT feeders – PARASITIC
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Puncture roots with STYLET, hollow
needle
Can be ENTRY POINT for other
organisms
SOIL BIOLOGY - MACROORGANISMS
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NEMATODES
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IMPORTANT CHARACTERISTICS
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Most common in POROUS SOILS
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DISTRIBUTE Bacteria and Fungi throughout soil
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USEFUL INDICATORS of a HEALTHY SOIL FOOD WEB
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The greater DIVERSITY of NEMATODES in a soil, means there
are a lot of DIFFERENT CRITTERS to FEED on
SOIL BIOLOGY - MACROORGANISMS
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ARTHROPODS
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MULTI-CELLULAR
INVERTEBRATES (no skeleton)
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JOINTED LEGS
EXOSKELETONS
4 TYPES
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INSECTS – Springtails, Beetles, Ants
CRUSTACEANS – Sow bugs
ARACHNIDS – Spiders, Mites
MYRAPODS – Centipedes, Millipedes, scorpions
SOIL BIOLOGY - MACROORGANISMS
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ARTHROPODS
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IMPORTANT CHARACTERISTICS
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Exist in the TOP 3” of SOIL
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SHRED and MIX OM, breaks down faster
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IMPROVES SOIL STRUCTURE by BURROWING
and adding FECAL PELLETS
SOIL BIOLOGY - MACROORGANISMS
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EARTHWORMS
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Segmented INVERTEBRATES
MULTI-CELLULAR organisms
Sexual REPRODUCTION
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3 TYPES
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EPIGEIC – LITTER dwellers
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ENDOGEIC - SHALLOW soil (top to 12” down)
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Compost piles - Red Wigglers
Not permanent burrows
ANECIC – DEEP BURROWING (to 6’ down)
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Night crawlers
Permanent BURROWS
SOIL BIOLOGY - MACROORGANISMS
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EARTHWORMS
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IMPORTANT CHARACTERISTICS
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TURN SOIL OVER
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IMPROVE SOIL STRUCTURE with BURROWS (biopores)
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Most abundant in LOAM, where MOISTURE, O2, and NEUTRAL pH
SOIL BIOLOGY - MACROORGANISMS
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MAMMALS
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RODENTS
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Highest concentration in
UNDISTURBED SOILS
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Gophers, Woodchucks,
Prairie Dogs, Moles, Voles
Pasture, Forest, Prairie
IMPORTANT
CHARACTERISTICS
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REJUVENATION of soil
by BURROWING and
MIXING SOIL
HORIZONS
SUMMARY - SOILFOOD WEB
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Researchers have not defined how much or what kind of
DIVERSITY is BEST for the SOIL FOOD WEB
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WHAT WE DO KNOW:
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Greater BIODIVERSITY = Greater STABILITY of the WEB
NUTRIENT CYCLING - More ORGANISMS – FASTER cycling
NUTRIENT RETENTION
IMPROVED STRUCTURE
DISEASE SUPPRESSION
DEGRADE POLLUTANTS
SUMMARY - SOILFOOD WEB
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WHAT does this mean for LAND MANAGEMENT?
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Less FERTILIZER
Greater INFILTRATION, Less EROSION
Less PESTICIDES
Greater WATER QUALITY