Midden Madness

The Faroe Islands honored the common earthworm, Lumbricus terrestris, on its postage stamp!

The Faroe Islands honored the common earthworm, Lumbricus terrestris, on its postage stamp!

Between collecting water samples, soil samples, and cover crop biomass, our Iowa Learning Farms team has spent the last several weeks hittin’ the old dusty trail (or should we say pounding the pavement?) as we travel to our field demonstration/research sites across the state. However, that’s not all that we’re sampling…  the amazing, aerating earthworm is on our radar, as well, thanks to a USDA-NRCS Conservation Innovation Grant.

Many farmers and gardeners quickly recognize the presence of earthworms as a good thing, aiding in fertilization and aeration of the soil. It’s true, earthworms are an excellent biological indicator of soil health!

The common nightcrawler, Lumbricus terrestris, is a deep-burrowing worm species, and it tends to live fairly permanently in one single tunnel or burrow. The earthworms come up to the soil surface at night or after a rain to feed, consuming things like corn stalks, bean stubble, and fresh cover crop residue. The earthworms then pull that plant material back into their tunnel, leaving a well-defined clumpy mound, or midden, on the soil surface.

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DSCN9147In general, one midden = one earthworm. Knowing this, we are able to count the middens to determine the presence and abundance of earthworms in different field plots across the state!

EarthwormCounts-MeganWe are especially interested in comparing earthworm counts in side-by-side strips with and without cover crops, so we’re visiting multiple sites across the state that are a part of the Iowa Cover Crop Working Group’s long-term cereal rye cover crop project. That study is currently looking at cover crop effects on crop yield and soil health, so the earthworm data will be one more piece of the puzzle.

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Stay tuned for further information and results of our earthworm counts as the season goes on!

Ann Staudt