Guest Blog: Digging for Worms

Today’s guest blogger is Iowa Learning Farms/Water Rocks! student intern Megan Koppenhafer.  Originally hailing from Williamsburg, IA, Koppenhafer is entering her junior year at Iowa State University, where she is double majoring in Environmental Science and Community and Regional Planning.  Growing up on a farm, she spent a lot of childhood days in the outdoors, and she is really thankful for having a summer job that also allows her to spend much of her working time outdoors!

As a child, whenever I would go fishing at summer camp I would dig in the soil after a good rain looking for worms to use as bait. I remember madly tearing under the mulch in the playground or in the soft sod next to the sidewalk. It was like finding a slimy treasure each time. I had the pleasure of watching my own campers’ joy in finding the worms last summer when I worked at a camp in Iowa City.

This summer I found myself enjoying my first couple of weeks of the internship but longing for more of the same contact with the soil that I’d had as a camper and camp counselor. Summer just feels like the time to do that kind of thing! There’s something about digging in the soil that makes you feel like you are accomplishing something.

Megan Koppenhafer, Ben Schrag, and Jessica Rehmann searching the soil for evidence of earthworms at research plots west of Ames.

Megan Koppenhafer, Ben Schrag, and Jessica Rehmann searching the soil for evidence of earthworms at research plots west of Ames.

This past week I began a new research project that would allow me to play in the soil like the days of old. So with four others, two interns and two full-time staff members, we embarked to count earthworm middens.

A clear shot of an “un-capped” earthworm hole; the little clump of soil and residue to the right is the midden.

A clear shot of an “un-capped” earthworm hole; the little clump of soil and residue to the right is the midden.

What are earthworm middens, you may ask? These are indicators of holes which are inhabited by nightcrawlers, and specifically, the midden is the mound of soil and plant matter over the hole. The Iowa Learning Farms group was looking for ways to detect changes in soil health in a way that would be easy and inexpensive to carry out. Because earthworms are a good indicator of soil health, we are counting middens to see if there is a correlation between the number of earthworms in crop fields related to the presence or absence of cover crops (in this case, cereal rye).

We are counting middens at 5 farms around the state this June. One of these is a research farm and the others are on farmers’ land, which are long term rye sites. The counting only happens once a year and it happens in June because the corn/soybean crops are still small enough to see the ground without much difficulty, and the cover crop residues are still present. This means the worms have fresh food to chow down on!

When we step onto the field we are armed with a PVC frame, clipboard, pen, and scissors. Typical plots with and without cover crops are below:

Soybean plot with cereal rye residue

Soybean plot with cereal rye residue (June 2, 2015)

Soybean plot without cereal rye ( June 2, 2015)

Soybean plot without cereal rye ( June 2, 2015)

We spend about 10 minutes with each frame as we carefully scrutinize the soil for middens:

Carefully examining the soil for signs of earthworm activity in a  soybean plot with cover crops.

Carefully examining the soil for signs of earthworm activity in a soybean plot west of Ames (June 2, 2015)

Each field site includes multiple replicated strips with cover crops/no cover crops, and we count 4-5 frames in every individual plot.

I can’t help but remember how imperfect our science was back in those camp days. I now have the secret to getting the perfect fish bait, but alas, not a fish to feed them to! That’s okay though, I am happy to leave the worms in the soil doing what they do best, making the soil a better place for the plants that grow there.

Megan Koppenhafer

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