1. Put the funnel in the rack. Make sure it is level. Fill it with clean water. Remove air bubbles by squeezing the rubber tube, or by draining water by opening the clamp.
2. Carefully mix the soil sample (excessive mixing will kill nematodes). Take a 10-g subsample, spread it out on a double layer of Kimwipe tissue. Record sample weight. Place the sample on the screen in the funnel. Do this carefully, so that small soil particles do not get through the tissues and obscure nematode samples.
3. The soil should be moist enough, but not totally submerged. Adjust the water level in the funnel using a spray bottle (don't spray on the sample, for same reasons as discussed in step two), or drain by opening the clamp. Cover the funnel with a petri dish or wax paper to avoid dust and evaporation.
4. The extraction time is 2 to 4 days. The longer the time, the more nematodes are harvested, but the question arises whether this increase is because of catching slow-moving nematodes, or due to hatchlings from eggs in the soil or larvae from fast-reproducing species—some have a life cycle of 2 days (especially at lab temperature). For that reason, 48 hours is an optimal time. Check after the first 24 hours if the soil is still moist enough.
aNematode extraction from plant and litter material: Cut the material in small pieces before extraction.
5. Harvest: By opening the clamp, get approximately 10mL in a centrifuge tube (e.g., plastic Corning, 15mL with screw cap). Store immediately under refrigeration, for maximum of 1 week. To kill and preserve (using 5% formaldehyde) the nematodes, see article about identification of nematode feeding groups by Yeates et al. (1993).
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