Upcoming Workshops, Seminars and Talks
February 15-19, 2010
Soil Foodweb Oregon (Corvallis) A weeklong workshop with an introduction taught by Dr. Ingham and compost technologies taught by Matt Slaughter, director of Soil Foodweb Oregon. There will also be a microscope class taught at the end of the week. Participants must supply their own microscopes.
Active fungi and bacteria on soil organic matter
Many species of fungi and bacteria in soil particles decompose soil organic matter. The fungi and bacteria that can break down the woody tissues and cellulose of intact leaves, stems and dead roots of plants perform the function of decomposition of organic matter that often builds humus and returns nutrient back to the soil. When the species that are capable of decomposition are lacking, leaves and other organic matter remain intact and the food energy they contain are not released to drive the foodweb.
Active fungi in root
Active fungi growing along the surface and within the tissue of a plant root as seen under fluorescent microscopy. This is probably an early stage of colonization of a section of root by a species of beneficial vesicular-arbuscular mycorrhizae, or "VAM" fungus that will form a symbiotic relationship with the root. Where the VAM is present, that portion of the root will be protected from root rot fungi and parasitic nematodes.
Soil protozoa that eat bacteria
Soil protozoa feed on bacteria in soil keeping bacterial communities growing and releasing nitrogen in plant available forms around roots. This active ciliate was stained with flourescein dye, then visualized with Differential Interference Contrast Microscopy.
Bacteria-feeding Nematode
Example of a species of beneficial nematode that feeds on bacteria and not plant roots. Bacteria are high in protein that in turn is high in nitrogen. When nematodes like this eat bacteria they digest the protein and convert it to nitrogen which is excreted as a body waste product back into the soil in a form that becomes available to plants. This function of nutrient recycling is how the soil foodweb can help turf stay green or help produce food crops with less need for chemical fertilizers, hence less chance of pollution.
Fungal-feeding nematode
Example of a beneficial nematode that feed on soil fungi. Fungi are high in protein that in turn is high in nitrogen. Nematodes that feed on fungi digest the protein they take in and convert it to a form of nitrogen that is excreted into the soil as a body waste product. This nitrogen is converted into nitrate and is available to plants. This is an example of the function of nutrient recycling that is a benefit of the soil foodweb. Where this feeding and gradual release of nitrogen occurs less applied chemical nitrogen is required during the growing season.
Predatory nematode that eats other nematodes
Example of a beneficial species of nematode that hunts and eats other nematodes in the soil. Predatory nematodes help balance the populations of all other kinds of nematodes. Body waste products recycle nitrogen and other nutrients back into the soil. Predatory nematodes should be present in a balanced soil foodweb. These are very large nematodes that are easily killed by plowing and other physical disturbance of soils.
Root-Feeding Nematode
Some root-feeding nematodes like the ring nematode above migrate in soil while feeding on roots. When populations of these nematodes increase to economic threshold levels, plant health and productivity will be reduced.
Endomycorrhizae with DIC microscope
Sections of plant roots that are colonized internally by beneficial symbiotic fungi. The blue structures are the portion of the vesicular-arbuscular mycorrhizae or "VAM" fungus that forms inside individual cells of the root tissue. Hyphae of the VAM fungus reach out into the soil to collect phosphorus, other nutrients and water which are transported back for use by the host plant. Most kinds of plants should be host to this form of colonization by VAM. Where VAM is present the plant is protected from root rot disease and parasitic nematodes. Most agricultural soils that have received high amounts of chemicals are deficient in VAM which means that higher rates of fertilizers and fungicides are usually required.
Endomycorrhizae with DIC light
This is a segment of a feeder root of a plant as seen through the microcope. The blue structures within the root are the nutrient absorbing part of a symbiotic fungus that lives partially within the root cells of host plants. These fungi and called vesicular-arbuscular mycorrhizae, or "VAM" and should be found colonizing a large percent of the root system of most plants. These VAM fungi bring phosphorus, other minerals and water from the soil to the root and protect the root from parasitic nematodes and root rot fungi. Many agriculutural soils that have received high inputs of chemicals are deficient in this component of the soil foodweb.
Ectomycorrhizae on tree roots
Example of Ectomycorrhizae on tree roots. This is a highly desirable colonization of tree and shrub roots that causes the very shape of the root branching pattern to change. Roots in this condition are very efficient at absorbing phosphorus, other nutrients and water. Also where this symbiotic colonization is present the roots are protected from root rot fungi and parsitic nematodes. Trees and landscape shrubs are often planted into a site where the symbiotic fungus is lacking, causing the plants to lack vigor and often eventually die.
Vesicules of endomycorrhizae in root
A section of plant feeder root that is heavily colonized by a desirable fungus called "endomycorrhizae". The structures within the root were nutrient-absorbing "arbuscules" that have converted to "vesicles" or spores. Another name for endomycorrhizae is "vesicular-arbuscular mycorrhizae ", or VAM. Where VAM is colonizing a root, that portion will be protected from root rot fungi and parasitic nematodes. VAM are symbiotic with plant roots. They take some nutrients from the sap that the plant can afford and reach out into the soil for phosphorus, other minerals and water.
Pythium Spores
Spores of Pythium spp. root rot fungus in a plant root. An example of disease that can occur where the soil foodweb is degraded or lacks diversity that would otherwise suppress root rot.
Fungal Strands in Compost
Strands seen with the naked eye.
Beneficial fungus in the soil
Example of a beneficial fungi.