We study nematodes. Nematodes live in the soil. In order to count them and identify them, we have to get them OUT of the soil, efficiently and quickly, taking care not to kill or injure them. This is not easy, but we are professionals.

First we weigh out the fresh soil (we also weigh out a bit to put in the drying oven to determine soil moisture) into a plastic tri-pour container. This is typically Ed’s job.

Ed weighing soil

Then we give the nematodes a bath. We add water to the soil, stir it gently, pour it through a set of sieves (the top sieve catches the large soil particles, the bottom sieve catches the nematodes and fine silts and clays) and wash them into a centrifuge tube. Diana and Breana like this job the most.

Breana sieving out nematodes

The tube containing the sample is centrifuged for five minutes. This is Byron’s job. Centrifuging forces all the worms and remaining soil into the bottom of the tube, creating a pellet. The liquid is poured off into a waste jar, saturated sugar water is added to the tube and it is mixed. Nematodes do not like the sugar, and they become suspended in the thick liquid. The tube is centrifuged again, this time only for a minute. All the soil is spun into the bottom of the tube, and the nematodes are floating in the sugar water.

Byron centrifuging nematodes

The tube is passed back to Breana or Diana, who pour the liquid through another fine screen, carefuly not to get any of the soil from the bottom of the tube onto the screen. The nematodes are washed gently with water and into another tube. This technique allows us to get a clean sample. That way, when we are looking under the microscope, we don’t have to move soil particles out of the way to see the soil animals (along with nematodes, we also find tardigrades, rotifers and the occasional mite). At the scope, we count the number of each species that we find, including whether they are male, female, or juvenile, and whether they are dead or alive.

Counting Worms

The only problem with this method is that it creates a lot of washing up to do. Luckily, Ed is VERY good at washing dishes, and also at stacking them so that they all fit on the drying table. He is the only person who can do this without toppling them over. perhaps he missed his calling as an architect?

Tri-pour tower

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