SOIL BIOLOGY

There are a DIVERSITY of ORGANISMS in SOIL There are a DIVERSITY of ORGANISMS in SOIL SIZE SIZE MICROORGANISMS MICROORGANISMS MACROORGANISMS MACROORGANISMS What they EAT or PRODUCE What they EAT or PRODUCE PRODUCERS PRODUCERS HERBIVORES HERBIVORES PREDATORS PREDATORS PARASITES PARASITES DECOMPOSERS DECOMPOSERS PREFERRED ENVIRONMENT PREFERRED ENVIRONMENT AEROBIC – O 2 AEROBIC – O 2 ANAEROBIC – without O 2 ANAEROBIC – without O 2

CYCLES CYCLES Focus on NUTRIENT CYCLING and the PROCESS Focus on NUTRIENT CYCLING and the PROCESS

WEBS WEBS Focus on ORGANISMS within the WEB Focus on ORGANISMS within the WEB

WEBS WEBS COMPLEX COMPLEX

SOIL ORGANIC MATTER - FOOD for the WEB SOIL ORGANIC MATTER - FOOD for the WEB ORGANIC MATTER is the portion of soil that contains PLANT and ANIMAL RESIDUES at various levels of DECAY ORGANIC MATTER is the portion of soil that contains PLANT and ANIMAL RESIDUES at various levels of DECAY

Most OM is made of CHEMICALLY COMPLEX C Compounds Most OM is made of CHEMICALLY COMPLEX C Compounds CARBOHYDRATES – long chains of simple sugars CARBOHYDRATES – long chains of simple sugars SUGARS SUGARS STARCHES STARCHES CELLULOSE – primary cell walls of live cells CELLULOSE – primary cell walls of live cells LIGNIN - secondary cell walls that make cells rigid, dead cells LIGNIN - secondary cell walls that make cells rigid, dead cells PROTEINS – long chains of N containing compounds (amino acids) PROTEINS – long chains of N containing compounds (amino acids)

ORGANIC MATTER DECOMPOSITION ORGANIC MATTER DECOMPOSITION ACTIVE OM - OM easily DECOMPOSED by MICROBES ACTIVE OM - OM easily DECOMPOSED by MICROBES ORGANIC COMPOUNDS leaked from roots ORGANIC COMPOUNDS leaked from roots Sloughed off ROOT PARTS Sloughed off ROOT PARTS DEAD OM DEAD OM MICROBES use RESPIRATION to break down OM MICROBES use RESPIRATION to break down OM OM + O 2 →→→→ CO2 + H2O + HUMUS OM + O 2 →→→→ CO2 + H2O + HUMUS (respiration) (respiration) Occurs RAPIDLY – weeks to months Occurs RAPIDLY – weeks to months

HUMUS – OM that RESISTS DECAY HUMUS – OM that RESISTS DECAY HUMUS is DARK and made of tiny, CLAY sized particles HUMUS is DARK and made of tiny, CLAY sized particles OXIDATION – chemical decomposition of HUMUS OXIDATION – chemical decomposition of HUMUS HUMUS + O 2 →→→→ CO2 + H2O HUMUS + O 2 →→→→ CO2 + H2O (oxidation) (oxidation) Occurs SLOWLY - 1-3% loss of HUMUS / year Occurs SLOWLY - 1-3% loss of HUMUS / year

NUTRIENT CYCLING of OM NUTRIENT CYCLING of OM PLANTS can only use NUTRIENTS in simple INORGANIC IONS PLANTS can only use NUTRIENTS in simple INORGANIC IONS When NUTRIENTS are TIED UP in the BODIES of living ORGANISMS or in FRESH OM they cannot be used by plants When NUTRIENTS are TIED UP in the BODIES of living ORGANISMS or in FRESH OM they cannot be used by plants This is called IMMOBILIZATION This is called IMMOBILIZATION Keeps NUTRIENTS from LEACHING Keeps NUTRIENTS from LEACHING When MICROBES break down COMPLEX ORGANIC FORMS to SIMPLER INORGANIC FORMS that PLANTS CAN USE When MICROBES break down COMPLEX ORGANIC FORMS to SIMPLER INORGANIC FORMS that PLANTS CAN USE This is called MINERALIZATION This is called MINERALIZATION When MICROBES EXCRETE, DIE, or are EATEN by another ORGANISM they will RELEASE NUTRIENTS that plants can use When MICROBES EXCRETE, DIE, or are EATEN by another ORGANISM they will RELEASE NUTRIENTS that plants can use

DISTRIBUTION of SOIL BIOLOGY DISTRIBUTION of SOIL BIOLOGY Top 2’ of SOIL – O and A Horizons Top 2’ of SOIL – O and A Horizons Most O2 Most O2 Most H2O Most H2O Most OM Most OM Best SOIL STRUCTURE Best SOIL STRUCTURE RHIZOSPHERE RHIZOSPHERE Where LEAKING and SLOUGHING occurs Where LEAKING and SLOUGHING occurs BACTERIAL dominated BACTERIAL dominated

DISTRIBUTION of SOIL BIOLOGY DISTRIBUTION of SOIL BIOLOGY LITTER LAYER and in HUMUS LITTER LAYER and in HUMUS FUNGAL dominated where COMPLEX C compounds FUNGAL dominated where COMPLEX C compounds SOIL PORES SOIL PORES Protozoa and Nematodes in water films Protozoa and Nematodes in water films Arthropods, Earthworms in air spaces Arthropods, Earthworms in air spaces

SOIL ORGANISM ACTIVITY SOIL ORGANISM ACTIVITY DEPENDS on MOISTURE and TEMP DEPENDS on MOISTURE and TEMP As MOISTURE & TEMPERATURE increases, ACTIVITY increases As MOISTURE & TEMPERATURE increases, ACTIVITY increases SOME ORGANISM is always ACTIVE SOME ORGANISM is always ACTIVE

BACTERIA BACTERIA MOST ABUNDANT MOST ABUNDANT SINGLE CELLED MICROSCOPIC organisms SINGLE CELLED MICROSCOPIC organisms RHIZOSPHERE RHIZOSPHERE 4 MAJOR 4 MAJOR DECOMPOSERS – consume SIMPLE C compounds DECOMPOSERS – consume SIMPLE C compounds SAPROPHYTIC SAPROPHYTIC MUTUALISTS – N FIXERS MUTUALISTS – N FIXERS BENEFICIAL relationship with PLANTS BENEFICIAL relationship with PLANTS Reside in ROOT NODULES Reside in ROOT NODULES Take atmospheric N 2 and convert to NH 4+ Take atmospheric N 2 and convert to NH 4+ PLANTS get NH 4+ and BACTERIA get simple sugars PLANTS get NH 4+ and BACTERIA get simple sugars

BACTERIA BACTERIA 4 MAJOR 4 MAJOR PATHOGENS - FEED on plant ROOTS PATHOGENS - FEED on plant ROOTS CHEMOTROPHS (or LITHOTROPHS) CHEMOTROPHS (or LITHOTROPHS) FEED on INORGANIC COMPOUNDS of N, S, Fe, or H FEED on INORGANIC COMPOUNDS of N, S, Fe, or H Important to N CYCLE Important to N CYCLE Some good at DEGRADING POLLUTANTS Some good at DEGRADING POLLUTANTS

BACTERIA BACTERIA 2 ODD BALLS 2 ODD BALLS PHOTOSYNTHETIC CYANOBACTERIA PHOTOSYNTHETIC CYANOBACTERIA PRODUCERS PRODUCERS Increase OM in soils Increase OM in soils Live in WATER FILMS Live in WATER FILMS ACTINOMYCETES ACTINOMYCETES FILAMENTOUS bacteria FILAMENTOUS bacteria Give soil EARTHY SMELL (geosmins) Give soil EARTHY SMELL (geosmins) DEGRADE COMPLEX C compounds DEGRADE COMPLEX C compounds PRODUCE ANTIBIOTICS that can inhibit growth PRODUCE ANTIBIOTICS that can inhibit growth Tolerant of DRY, HIGH TEMP and HIGH pH soils Tolerant of DRY, HIGH TEMP and HIGH pH soils Most are SAPROPHYTIC, some PARASITIC Most are SAPROPHYTIC, some PARASITIC

BACTERIA BACTERIA IMPORTANT ROLES of BACTERIA IMPORTANT ROLES of BACTERIA IMMOBILIZATION / MINERALIZATION of NUTRIENTS IMMOBILIZATION / MINERALIZATION of NUTRIENTS Produce GUMS that BIND soil particles and BUILD SOIL STRUCTURE Produce GUMS that BIND soil particles and BUILD SOIL STRUCTURE Some FILTER and DEGRADE POLLUTANTS Some FILTER and DEGRADE POLLUTANTS DOMINANT in NEUTRAL pH soils and GRASSLANDS DOMINANT in NEUTRAL pH soils and GRASSLANDS

FUNGI FUNGI FEWER numbers of FUNGI in soil, but makes up the LARGEST MASS FEWER numbers of FUNGI in soil, but makes up the LARGEST MASS FILAMENTOUS, MULTI-CELLULAR organisms FILAMENTOUS, MULTI-CELLULAR organisms HYPHAE HYPHAE MYCELIUM MYCELIUM 4 TYPES 4 TYPES DECOMPOSERS – SAPROPHYTIC DECOMPOSERS – SAPROPHYTIC COMPLEX C compounds COMPLEX C compounds Excrete organic ACIDS which increase HUMUS Excrete organic ACIDS which increase HUMUS

4 TYPES 4 TYPES MUTUALISTS - MYCORRHIZAE (fungus – root) MUTUALISTS - MYCORRHIZAE (fungus – root) ECTOmycorrhizae ECTOmycorrhizae Forms a MANTLE surrounding ROOT and IN BETWEEN CELLS Forms a MANTLE surrounding ROOT and IN BETWEEN CELLS Artificially grown and INOCULATED Artificially grown and INOCULATED ENDOmycorrhizae – AM (VAM) ENDOmycorrhizae – AM (VAM) Grows INTO CELLS of roots and forms ARBUSCLES (nutrient transfer), VESCICLES (storage) Grows INTO CELLS of roots and forms ARBUSCLES (nutrient transfer), VESCICLES (storage) Cannot be artificially grown Cannot be artificially grown ECENDOmycorrhizae (minor type) ECENDOmycorrhizae (minor type) Intermediate type seen in nurseries and after forest fires Intermediate type seen in nurseries and after forest fires Thin mantle and some cell penetration, but turns into ECTO as matures Thin mantle and some cell penetration, but turns into ECTO as matures Increases ABSORPTION of P, Zn, Cu, H 2 O Increases ABSORPTION of P, Zn, Cu, H 2 O Some PROTECT PLANT from diseases causing PATHOGENS Some PROTECT PLANT from diseases causing PATHOGENS

FUNGI FUNGI 4 TYPES 4 TYPES PATHOGENS - DISEASE causing organisms PATHOGENS - DISEASE causing organisms PREDATORS PREDATORS NEMATODE eating fungi NEMATODE eating fungi

FUNGI FUNGI IMPORTANT CHARACTERISTICS of FUNGI IMPORTANT CHARACTERISTICS of FUNGI O Horizon for COMPLEX C compounds O Horizon for COMPLEX C compounds AEROBIC soils AEROBIC soils DOMINATE ACID soils, FOREST soils DOMINATE ACID soils, FOREST soils DETRIMENTAL HABITATS DETRIMENTAL HABITATS TILLAGE TILLAGE FUNGICIDE use FUNGICIDE use High N or P FERTILIZER use High N or P FERTILIZER use Fallowed FIELDS Fallowed FIELDS Non-Mycorrhizae CROPS Non-Mycorrhizae CROPS

PROTOZOA PROTOZOA SINGLE CELLED organisms SINGLE CELLED organisms 3 TYPES 3 TYPES CILIATES CILIATES AMOEBA AMOEBA FLAGELLATES FLAGELLATES FEED on BACTERIA FEED on BACTERIA C : N ratio BACTERIA, 4 - 5: 1 C : N ratio BACTERIA, 4 - 5: 1 C : N ratio PROTOZOA, 10 : 1 C : N ratio PROTOZOA, 10 : 1 As feed on bacteria EXCRETE excess N as NH 4+ (mineralization) As feed on bacteria EXCRETE excess N as NH 4+ (mineralization)

NEMATODES NEMATODES Non – segmented, EEL-LIKE WORMS, 1/20” long Non – segmented, EEL-LIKE WORMS, 1/20” long MULTI-CELLULAR organisms MULTI-CELLULAR organisms PRODUCE EGGS in masses PRODUCE EGGS in masses

NEMATODES NEMATODES 5 TYPES – based on what they FEED on 5 TYPES – based on what they FEED on BACTERIAL feeders BACTERIAL feeders FUNGAL feeders FUNGAL feeders PREDATORS PREDATORS OMNIVORES OMNIVORES PLANT ROOT feeders – PARASITIC PLANT ROOT feeders – PARASITIC Puncture roots with STYLET, hollow needle Puncture roots with STYLET, hollow needle Can be ENTRY POINT for other organisms Can be ENTRY POINT for other organisms

NEMATODES NEMATODES IMPORTANT CHARACTERISTICS IMPORTANT CHARACTERISTICS Most common in POROUS SOILS Most common in POROUS SOILS DISTRIBUTE Bacteria and Fungi throughout soil DISTRIBUTE Bacteria and Fungi throughout soil USEFUL INDICATORS of a HEALTHY SOIL FOOD WEB USEFUL INDICATORS of a HEALTHY SOIL FOOD WEB The greater DIVERSITY of NEMATODES in a soil, means there are a lot of DIFFERENT CRITTERS to FEED on The greater DIVERSITY of NEMATODES in a soil, means there are a lot of DIFFERENT CRITTERS to FEED on

ARTHROPODS ARTHROPODS MULTI-CELLULAR MULTI-CELLULAR INVERTEBRATES (no skeleton) INVERTEBRATES (no skeleton) JOINTED LEGS JOINTED LEGS EXOSKELETONS EXOSKELETONS 4 TYPES 4 TYPES INSECTS – Springtails, Beetles, Ants INSECTS – Springtails, Beetles, Ants CRUSTACEANS – Sow bugs CRUSTACEANS – Sow bugs ARACHNIDS – Spiders, Mites ARACHNIDS – Spiders, Mites MYRAPODS – Centipedes, Millipedes, scorpions MYRAPODS – Centipedes, Millipedes, scorpions

ARTHROPODS ARTHROPODS IMPORTANT CHARACTERISTICS IMPORTANT CHARACTERISTICS Exist in the TOP 3” of SOIL Exist in the TOP 3” of SOIL SHRED and MIX OM, breaks down faster SHRED and MIX OM, breaks down faster IMPROVES SOIL STRUCTURE by BURROWING IMPROVES SOIL STRUCTURE by BURROWING and adding FECAL PELLETS

EARTHWORMS EARTHWORMS Segmented INVERTEBRATES Segmented INVERTEBRATES MULTI-CELLULAR organisms MULTI-CELLULAR organisms Sexual REPRODUCTION Sexual REPRODUCTION 3 TYPES 3 TYPES EPIGEIC – LITTER dwellers EPIGEIC – LITTER dwellers Compost piles - Red Wigglers Compost piles - Red Wigglers ENDOGEIC - SHALLOW soil (top to 12” down) ENDOGEIC - SHALLOW soil (top to 12” down) Not permanent burrows Not permanent burrows ANECIC – DEEP BURROWING (to 6’ down) ANECIC – DEEP BURROWING (to 6’ down) Night crawlers Night crawlers Permanent BURROWS Permanent BURROWS

EARTHWORMS EARTHWORMS IMPORTANT CHARACTERISTICS IMPORTANT CHARACTERISTICS TURN SOIL OVER TURN SOIL OVER IMPROVE SOIL STRUCTURE with BURROWS (biopores) IMPROVE SOIL STRUCTURE with BURROWS (biopores) Most abundant in LOAM, where MOISTURE, O 2, and NEUTRAL pH Most abundant in LOAM, where MOISTURE, O 2, and NEUTRAL pH

MAMMALS MAMMALS RODENTS RODENTS Gophers, Woodchucks, Prairie Dogs, Moles, Voles Gophers, Woodchucks, Prairie Dogs, Moles, Voles Highest concentration in UNDISTURBED SOILS Highest concentration in UNDISTURBED SOILS Pasture, Forest, Prairie Pasture, Forest, Prairie IMPORTANT CHARACTERISTICS IMPORTANT CHARACTERISTICS REJUVENATION of soil by BURROWING and MIXING SOIL HORIZONS REJUVENATION of soil by BURROWING and MIXING SOIL HORIZONS

Researchers have not defined how much or what kind of DIVERSITY is BEST for the SOIL FOOD WEB Researchers have not defined how much or what kind of DIVERSITY is BEST for the SOIL FOOD WEB WHAT WE DO KNOW: WHAT WE DO KNOW: Greater BIODIVERSITY = Greater STABILITY of the WEB Greater BIODIVERSITY = Greater STABILITY of the WEB NUTRIENT CYCLING - More ORGANISMS – FASTER cycling NUTRIENT CYCLING - More ORGANISMS – FASTER cycling NUTRIENT RETENTION NUTRIENT RETENTION IMPROVED STRUCTURE IMPROVED STRUCTURE DISEASE SUPPRESSION DISEASE SUPPRESSION DEGRADE POLLUTANTS DEGRADE POLLUTANTS

WHAT does this mean for LAND MANAGEMENT? WHAT does this mean for LAND MANAGEMENT? Less FERTILIZER Less FERTILIZER Greater INFILTRATION, Less EROSION Greater INFILTRATION, Less EROSION Less PESTICIDES Less PESTICIDES Greater WATER QUALITY Greater WATER QUALITY