The soil ecosystem has similar dynamics as the above-ground ecosystem with which we are more familiar - but in miniature! From an IPM standpoint, good soil health is critical to prevention of pest problems, especially related to infection of plants from plant pathogens. If plant roots are not functioning properly due to pest damage or poor soil quality, the plant cannot take up water and nutrients well. Sick plants are more susceptible to above-ground pests. There is a correlation between soil life and soil health. Understanding and promoting certain soil life and use of composting are two good ways to increase soil health and thus prevent pest problems from occurring.
Activity - Soil Fauna
Using the Berliese funnel method.
to give the audience an opportunity to view interesting soil life
Small soil organisms such as nematodes, mites, and collembola (springtails) are collected using a funnel, ring stand and light source. They can be viewed with a dissecting scope or magnifying glass. Note: this technique tends to extract collembola more efficiently than centrifugation.
- moist, biologically active soil or mature compost (can be collected and stored in a cool place in a closed plastic bag up to 24 hours)
- ring stand and ring
- funnel (needs to be opaque)
- small piece of window screening or 1/4 inch hardware cloth to fit into the bottom of the funnel to keep the soil from falling out. Note: larger organisms will not make it through the window screen. You can cut several slits in the screen or pick out the larger organisms before putting the soil in the funnel
- light source (25 watt)
- petri dish(es)
- magnifying glass or dissecting microscope
- 100 mL of 90% ethanol/10% glycerol solution (if you wish to preserve specimens)
- simple key of soil organisms likely to be seen
- light and dark colored paper to place under petri dishes for viewing
- Select a setup location for the funnel where it will not be bumped or agitated. Bumping and vibrating can cause the soil to loosen and fall into the collection jar, clouding the final solution.
- Place the screening inside the funnel so that it blocks off the opening at the bottom as shown in Figure 1. Put the funnel in the ring stand
- If you wish to collect live organisms, add 100mL of water into a beaker or jar or use solution of 90% ethanol and 10% glycerol if you wish to preserve them
- Place the beaker just below the funnel to collect the specimens
- Add a few handfuls of moist soil or compost to the funnel so that it rests on the screen, until you have a layer 6-8 cm (2-3 inches) deep. This has to be done carefully so soil does not sift through into the collection jar
- Position a 25-watt light source about the funnel, and close enough to the funnel so the heat from the bulb will warm the contents of the funnel (about 6 inches above the soil). The light, heat and drying will gradually drive the organisms downward through the funnel and into the collection jar. If the light source is too strong, the organisms will dry up and die before making it through the soil and into the funnel
- Leave the apparatus for one or two days to insure that most of the organisms are collected
- After collection, pour off some of the liquid from the collection jar into a petri-dish, filling it to about 2/3 its height. Observe the organisms under a dissecting microscope or with a magnifying glass. You may want to place white construction paper under the dish to view dark-colored insects, and dark paper for viewing the lighter-colored organisms.
- Provide a simple key of the organisms that are likely to be seen. One, showing distribution of typical organisms in a square foot of topsoil, is included with this package.
- Discuss the factors that influence numbers of soil organisms. Climate, vegetation, and the physical and chemical characteristics of soil all influence species composition and diversity
From Drinkwater, et al. July 2000. "Soil Health Demonstration Protocols". Rodale Institutuion Project #ENE96-26