My UCD colleagues and I sampled the field plots April 28th and 29th for earthworms and soils. By this time, more than 90% of the residues we had added to the plots had disappeared!
Imagine me kneeling on the ground (in the sun the first day, and in the rain the second day), searching through the blades of grass for a nice big earthworm burrow, like the one pictured above. Look, you can even see some of the mustard residue sticking out from the burrow opening. This was a good sign that this burrow was inhabited by Lumbricus terrestris, an earthworm who lives in deep in the soil but comes up to the surface to feed on plant litter.
For my research, I am particularly interested in the microbial communities that live within the walls of Lumbricus terrestris burrows. Why? There are several tons of bacteria and fungi in an acre of soil, but microorganisms are active only in certain soil "hot spots" where food and nutrients can be found. The lining of earthworm burrows (the "drilosphere) is such a hotspot because of the earthworm mucus and poo which are deposited along the walls, and so here you can find greater numbers and activity of microorganisms compared to other places in the soil. We don't know much about the diversity of microorganisms that live in the drilosphere, however, or how much carbon gets transferred from plant litter to drilosphere soil and into microbial communities, which is what I will be measuring.
To do this, I had to find L. terrestris burrows (first picture, above) and then excavate the soil around the burrow. In the second picture, you can see how I took a soil core around the burrow and sliced it into sections. I then used a small spatula to scrape away the soil within a few millimeters of the burrow (upper left portion of picture 2) to collect my drilosphere samples. I will be analyzing drilosphere soils for plant litter carbon content and microbial community composition shortly.
