For Release April 23, 2002

Earthworms; Friend or Foe?

AGRI-VIEWS
by Chuck Otte, Geary County Extension Agent

Does anyone ever think about earthworms? I mean really stop and take them into consideration? I donít think too many of us do. Earthworms are just always there. We dig up the garden and we see them. We get a night of heavy rain and we see soggy earthworms out on the driveway trying to keep from drowning. All we know about earthworms are that they are traditional fish bait and they are supposed to be good for the soil.

I often have to laugh when I hear someone say that earthworms are good. These people have obviously not been in some of the yards that I have. Some yards have so many night crawlers in them that have left so many bumps (soil castings) on the surface that you can hardly walk or run a lawnmower over it. I donít think that these homeowners consider earthworms to be their friends!

You may be surprised to know that we have many different species of earthworms in Kansas. Finding an exact number is tough, but there are probably over a half dozen species and could easily exceed a dozen. The other surprising fact is that very few of our Kansas worms are native species. Part of the problem goes clear back to the last glacial period. Any part of Kansas that was covered by glaciers in the last ice age probably has few, if any, native earthworms. The rest of us may have a few left.

Most of the dominant species that we see in gardens and yards are European species that were brought over by settlers for the last 400 years. Night crawlers, the standard sized earthworm, and even the smaller red worms are all imports. Once the first imported worms hit the ground, so to speak, on the east coast, the die was cast. Earthworms do migrate, advancing out from a point of origin at the rate of 5 to 10 yards per year. Naturally, soil moisture, or lack of it, will impact how far and where the worms will colonize.

As they moved into new areas they were more aggressive and better able to compete for food and space resources. What do worms eat by the way? Well, they eat organic matter in the soil. The eat the soil, digest the organic matter thatís in it, and then eject a very rich waste product. The castings that we see on the top of the ground are what the worms have eaten and passed through their system. Earthworms go a very good job of converting organic matter into plant usable products as well as aerating the soil.

But sometimes they do their job too well. In northern US and Canada hardwood forests, especially sugar maple forests, these imported worms are working through the leaf litter and organic matter so fast that the normal nutrient cycling has changed, soil life is being altered and erosion is starting to occur.

Is it anything we need to worry about here in Kansas? We donít really know, because worm researchers are few and far between. But caution and care is certainly in order! Gardeners need to be careful in transporting plants from far away. Fisherman need to not dump worms by the boat ramp at the end of their fishing trip. Take them home and use them the next trip.

Worms, something we often donít think about, yet even their lives are in massive turmoil. Worms, inherently good, but maybe sometimes too good! For interesting reading on earthworms visit the following web site: http://www.nrri.umn.edu/worms/.

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