THE SOIL FOOD WEB Copyright restrictions for photos in this presentation: The text and non-photo graphics are products of the USDA Natural Resources Conservation Service (NRCS). They may be used freely. Credit the USDA Natural Resources Conservation Service. Some photos are from the NRCS or ARS and may be used freely. Credit the USDA Natural Resources Conservation Service or USDA Agricultural Resource Service as appropriate. Photos from non-government sources were lent to the NRCS for use in the Soil Biology Primer and this slide set. Other uses may be restricted. Contact original source for permission. Credit (for this slide only): Courtesy of USDA Natural Resources Conservation Service. File names (for this slide only): MITEgray Handlowres amoeba

Soil Biology and the Landscape When you look across a landscape, imagine the microscale habitats and complex ecosystem under the surface. Credits: (drawing) S. Rose and E.T. Elliott; (photo) Arlene J. Tugel, USDA-NRCS File names: Rose, grass

The Soil Food Web Most people are familiar with the above-ground food web: Plants are eaten by herbivores are eaten by carnivores, and so on. But most plant matter is not eaten by herbivores; it is decomposed by the underground food web. All plants depend on the soil food web for their nutrition. File name: A-3 (145KB). (Also fw.jpg 574K, and fwb.jpg at 422K) Image courtesy of the USDA-NRCS.

Components of Soil Organic Matter Decomposing organic matter (active fraction) 33% - 50% Stabilized organic matter (humus) Fresh residue <10% Living organisms <5% Photo credit: Collohmannia sp. Roy A. Norton, College of Environmental Science & Forestry, State University of New York File name: M8 Mites and Leaf

Rhizosphere The rhizosphere is the narrow region where roots and soil meet. Soil biological activity is concentrated here. This photo shows cells, proteins, and sugars being released by the young root tip. Credit: No. 53 from Soil Microbiology and Biochemistry Slide Set.1976 J.P. Martin, et al., eds. SSSA, Madison, WI. File name: SST

Microbial Biomass with Depth File name: A-6. 445KB (Also depth.jpg at 170K) Image courtesy of USDA-NRCS

Seasonal Microbial Activity File name: A-7, 250KB (also Season.jpg at 1917K) Image credit: USDA-NRCS.

FOOD WEB & SOIL HEALTH Many effects of soil organisms are a result of the interactions among organisms, rather than the actions of individual species. This implies that managing for a healthy food web is not primarily a matter of inoculating with key species, but of creating the right environmental conditions to support a diverse community of species. Photo: A predacious mite (Labidostomatidae) feeds on a springtail. Photo credit: Roy A. Norton, State University of New York at Syracuse. File names: predacious mite, M10 Mite & springtail

Biomass of Soil Organisms in Four Ecosystems File name: biomassB.jpg, 237K (Also: Biomass.jpg at 299K and B-1 at 740KB) Image credit: USDA-NRCS.

Typical Numbers of Soil Organisms in Healthy Ecosystems Ag Land Prairie Forest Organisms per gram (teaspoon) of soil Bacteria 100 mil. -1 bil. Fungi Several yards 10s – 100’s of yds 1-40 miles (in conifers) Protozoa 1000’s 100,000’s Nematodes 10-20 10’s – 100’s 100’s Organisms per square foot Arthropods < 100 500-2000 10,000-25,000 Earthworms 5-30 10-50 (0 in conifers) Each type of ecosystem has a characteristic food web structure. Credit: USDA Natural Resources Conservation Service

Methods for Measuring the Food Web Counting Direct counts of individuals Plate counts of colonies Activity levels Respiration (CO2 production) Nitrification rates Decomposition rates Cellular constituents Biomass C, N, or P Enzymes Phospholipids DNA and RNA

Bacteria with fluorescent stain for counting Credit for both photos: Serita Frey, The Ohio State University File names: SF4 bact.jpg, SF1 bact.jpg

A Complex Food Web Image credit: USDA-NRCS. Source: Elaine Ingham and Andrew Moldenke. File name: CompFW.jpg, 509K. (Also: CompFWa.jpg at 478K, and ComplexWeb.eps at 272K.)

Complexity of the Soil Food Web in Several Ecosystems File name: Funct.jpg 382K Image credit: USDA-NRCS

Learning about the relationship between soil management and the soil food web requires the observations and field trials of land managers along with formal research. Credit: Arlene Tugel, USDA-NRCS Soil Quality Institute

BACTERIA Photo credit: Michael T. Holmes, Oregon State University, Corvallis File name: PBUT

Bacteria Bacteria are the specs on the fungal hyphae. The thicker, upright objects are root hairs. Credit: R. Campbell. In R. Campbell. 1985. Plant Microbiology. Edward Arnold; London. Pp. 116 and 149. Used with the permission of Cambridge University Press

Nitrogen-fixing Bacteria Nodules formed where Rhizobium bacteria infected soybean roots. File name: Nods on Beans.jpg 277K (Also C-2 at 580K shows whole box.) Photo credit: Stephen Temple, New Mexico State University.

Actinomycetes Bacterial cells that grow like fungal hyphae Photo credit: No. 14 from Soil Microbiology and Biochemistry Slide Set. 1976. J.P. Martin, et al., eds. SSSA, Madison, WI File name: SSSA14 Bacterial cells that grow like fungal hyphae

Bacteria vs. fungi In many systems, including grasslands and agricultural fields, the biomass of bacteria dominates the biomass of all other soil organisms. Fungi dominate the soil biomass of forest systems.

FUNGI Credit: Serita Frey, The Ohio State University File name: SF6

Fungi and Soil Quality Decompose carbon compounds Improve OM accumulation Retain nutrients in the soil Bind soil particles Food for the rest of the food web Mycorrhizal fungi Compete with plant pathogens Photo credit: No. 48 from Soil Microbiology and Biochemistry Slide Set. 1976. J.P. Martin, et al., eds. SSSA, Madison WI. File name: SSSA48

Mycorrhizal structure Mycorrhizae Tree root Photo credit: Randy Molina, Oregon State University, Corvallis. File name: M4 Fungi LR.jpg, 328K Fungal hyphae Mycorrhizal structure

Ectomycorrhizae Photo Credit: USDA, Forest Service, PNW Research Station, Corvallis, Oregon. File name: Ectomy~1

Arbuscular Mycorrhizae (AM) File name: VAM LR.jpg 205K Photo Credit: Elaine R. Ingham, Oregon State University, Corvallis.

File name: JER LR.jpg, 290K Photo Credit: Jerry Barrow, USDA-ARS Jornada Experimental Range, Las Cruces, NM.

Mushrooms: The fruiting body of some fungi File name: tettleshroom LR.jpg, 234K Photo courtesy of USDA-Natural Resources Conservation Service.

Mycorrhizal Fungi Endophytes (similar to mycorrhizae) and polysaccharides secreted by the plant and fungi bind sand to the root. Photo Credits: Jerry Barrow, USDA-ARS Jornada Experimental Range, Las Cruces, NM. File names: BWSHEATH COL-SH~1

PROTOZOA Ciliates Amoebae Flagellates Largest of the three types Move by means of hair-like cilia Eat the other protozoa and bacteria Amoebae Also large Move by means of a temporary foot (pseudopod) Include testate amoebae (with shell-like covering), and naked amoebae Flagellates Smallest of the three Move by means of a few whip-like flagella.

PROTOZOA File name: Testate amoeba LR.jpg, 179K Credit: Elaine R. Ingham, Oregon State University, Corvallis

Flagellate File name: vorticella prot LR.jpg, 278K Credit: Elaine R. Ingham, Oregon State University, Corvallis.

Ciliate File name: ciliate2 LR.jpg 294K Credit: Elaine R. Ingham, Oregon State University, Corvallis

Amoebae Photo credits: (brown photo) No. 35 from Soil Microbiology and Biochemistry Slide Set. 1976. J.P. Martin, et al., eds. SSSA, Madison, WI (blue photo) Michael T. Holmes, Oregon State University, Corvallis. (Not used in the Primer.) File names: (blue photo) AMOE (brown photo) SSSA35

Mineralization and Immobilization Organisms consume other organisms and excrete inorganic wastes. Organic nutrients are stored in soil organisms and organic matter. Inorganic nutrients are usable by plants, and are mobile in soil. File name: MinImmB.jpg, 51K. (Also: MinImmA.jpg at 100K, and E-2 at 375KB) Image courtesy of USDA-Natural Resources Conservation Service Organisms take up and retain nutrients as they grow.

Soil-Dwelling “Vampires” Vampyrellids are a group of amoebe that eat fungi by drilling round holes through the fungal cell wall and consumes the fluid inside. In this picture, they attack Gaeumannomyces graminis, the fungus that causes “take-all disease” in wheat. File name: vampraid.jpg, 451K (Also: E-4 at 1500KB, shows whole Bug Biography.) Photo credit: Homma, Y. et al. 1979. Phytopathology 69:1118-22. (Photo is in the public domain.)

NEMATODES File name: large todes LR.jpg, 262K Credit: Elaine R. Ingham, Oregon State University, Corvallis.

NEMATODES Top left is the bacterial-feeding nematode, Elaphonema. Bottom right is a fungal-feeding nematode. Photo credits: (for both) Elaine R. Ingham, Oregon State University, Corvallis File names: BFTODE FFTODE

Predatory Nematode File name: predatory tode LR.jpg 254K Credit: Kathy Merrifield, Oregon State University, Corvallis.

Root-feeding nematodes Upper left (blue) is the lesion nematode, Pratylenchus. Lower right is the root-feeding nematode, Trichodorus. File names: Upper Left (blue): rootfeedingtode prat LR.jpg, 233K Lower right: rootfeedingtode trich LR.jpg, 184K Credits: Upper Left, blue: Kathy Merrifield, Oregon State University, Corvallis. Lower right, green: Elaine R. Ingham, Oregon State University, Corvallis.

ARTHROPODS Collohmannia sp. Photo credit: Roy A. Norton, State University of New York at Syracuse. File name: M12

Mites and Biodiversity Credit: Valerie Behan-Pelletier, Agriculture and Agri-Food Canada. File name: VBPmites LR.jpg 287K

Types of Arthropods Shredders Predators Herbivores Fungal-feeders

Shredders: millipedes The millipede on the light background is Orthoporus ornatus. Photo Credits: (beetle) A. Beaumont, Lowestoft (millipede, brown background) No. 41 from Soil Microbiology and Biochemistry Slide Set. 1976. J.P. Martin, et al., eds. SSSA, Madison, WI (millipede, light background) David B. Richman, New Mexico State University. File names: (beetle) INSECT~3 (millipede) SSSA41 (millipede, light background) Orthopor 472K

Predators (1) (group of ants) Rugose harvester ants. Pogonomyrmex rugosus Photo credits: (Ant) David Houghton (not used in the Primer) (Group of ants) David B. Richman, New Mexico State University, Las Cruces. File names: DH ant

Predators (2): Pseudoscorpions With green background is a Homosphyronid. Credits: (green) David B. Richman, New Mexico State University, Las Cruces. File names: (green) Pseudo4 (461K) (yellow body) Pseudoscorpion.jpg

Predators (4): Centipedes Photo credits: (brown) No. 40 from Soil Microbiology and Biochemistry Slide Set. 1976. J.P. Martin, et al., eds. SSSA, Madison, WI (gray) David Houghton File names: (brown) SSSA40 (gray) DH centipede

Predators (5) Wolf spider Photo Credit: Trygve Steen, Portland State University, Portland, Oregon. File name: M6B

Herbivores Photo credits: (symphylan) Ken Gray Collection, Department of Entomology, Oregon State University, Corvallis. File names: (symphylan) M11 Symphylan

Springtails (fungal feeders) Abundant in many soils. Feed on some disease-causing fungi. Jump by slamming their tail down. Photo credits: (light microscope) Andrew R. Moldenke, Oregon State University, Corvallis. File names: (light microscope) M7B

What is in Your Soil? Pitfall trap Berlese funnel Burlese funnel – Heat from a light bulb dries soil and drives small arthropods into the cup below. Pitfall trap – Large arthropods fall into a cup buried with the rim even with the soil surface. (Click on “Reset Picture” to restore white background behind the drawings.) File names: berlese.jpg 139K, pitfall.jpg 92K Images courtesy of the USDA-Natural Resources Conservation Service Berlese funnel

EARTHWORMS Photo credit: Clive A. Edwards, The Ohio State University, Columbus. File name: CD1 ew bunch

Earthworms bury litter Photo credit: Soil and Water Management Research Unit, USDA-Agricultural Research Service, St. Paul, Minnesota. File name: LW leaf in burrow

Earthworm burrow Photo credit: Clive A. Edwards, The Ohio State University, Columbus. File name: CE3 burrow

Vertical burrows Photo and image credit: North Appalachian Experimental Watershed, USDA-Agricultural Research Service, Coshocton, Ohio

Earthworm casts Photo credit: Soil and Water Management Research Unit, USDA-Agricultural Research Service, St. Paul, Minnesota File name: LW6a casts

Earthworm burrow opening Photo credit: Clive A. Edwards, The Ohio State University, Columbus File name: CE7a2, 303K

Earthworm burrow opening Midden pile Photo credit: North Appalachian Experimental Watershed, USDA-Agricultural Research Service, Coshocton, Ohio File name: MS7b Burrow opening

Reproduction Credit for both photos: Clive A. Edwards, The Ohio State University, Columbus File names: CE8a-cocoon CE8c mating