earthworms – The Garden Professors™

Worm Juice!

There’s still snow on the ground, but I know that spring is finally coming to Minnesota because I FINALLY saw a crocus peeking its head out of the ground this week!

So perhaps you wonder from time to time what garden professor types get excited about. Well, here’s an example. Tomorrow I’ll be meeting up with a friend of mine, Meleah Maynard, which is nice, we always have a good time chatting, but I’m especially excited because she’s bringing me some drippings from her vermicomposting. Hooray, worm juice! I’ll be taking it to the lab and then running some tests on it to see what it has in it in terms of nutrients. After I get the results in a couple of weeks I’ll give you the information (maybe even compare it side by side with urine – that would be fun!)

Why did the worm cross the road?

…To get to the other side. Of course.

All the rain we’re having is causing the earthworms to crowd the sidewalks and driveways. They fling themselves out of the ground and onto the pavement because they’re drowning, right? Nope. Urban myth (by the way, why are there no Rural Myths?). The punchline is not too far off: they can only move about above ground while it’s raining. They use rain events to safely relocate, and can allegedly live for a while in a puddle. But we all know what happens when the sun comes out…crispy Ramen time.

I had just come in from flinging a bunch of worms off the pavement in front of our building – they were going to get mashed or eaten by robins otherwise. I probably put them right back from whence they came, against their earthwormy wishes.

Portrait of Two Worms
– by H.L. Scoggins

Then I read Bert’s post…it’s like reporting that the Easter Bunny has rabies or something. I’ve always been delighted to see earthworms, under any conditions. To the point of saving their squirmy little lives whenever possible. Not sure what to think about this new bit of information.

Invasion of the killer earthworms

It sounds like a B-grade horror movie. Millions of earthworms, moving silently beneath soil, wreaking havoc until the entire planet is uninhabitable. Sound a little far-fetched? Not to ecologists that study northern hardwood forests. While most of us grew up thinking earthworms were ubiquitous, turns out they are not native in parts of North America that were covered with ice during the last glacial period. Most of us also grew up thinking that earthworms where the good guys/girls (they’re hermaphroditic), churning up compacted soil and leaving nutrient-rich castings behind. In many northern hardwood forests, however, exotic earthworms, have become invasive and ecologists believe they are having profound effect on ecosystems.

I have to admit I hadn’t paid that much attention to the invasive earthworm issue but I attended a seminar last week by Dr. Lee Frelich, Director of the Center for Forest Ecology at the University of Minnesota. Dr. Frelich’s seminar touched on several areas of research, almost all of it extremely depressing, related to climate change and invasive species. He and his colleagues have documented significant changes in soil ecosystem processes and plant succession associated with increasing populations of earthworms. Nightcrawlers, in particular, cause a lot of problems because they consume fresh leaf litter causing it to decompose at a much faster rate compared to un-invaded ecosystems. The net result of these soil changes is that few trees or shrubs can reproduce in the understory. Over time this may lead to a very different looking forest than exists there today.

Of course, we may end up with a very different forest in any event, given some of the climate change scenarios Dr. Frelich presented. One worst-case model predicted the climate of the Boundary Waters area of Minnesota would resemble that of present-day Oklahoma City by the end of the century. But I try not to worry; I figure by that point I’ll be food for the earthworms anyway.

For more info on the earthworms that ate Minnesota, check out these links, if you dare…

http://www.scientificamerican.com/article.cfm?id=invasive-earthworms-denude-forests

http://www.dnr.state.mn.us/invasives/terrestrialanimals/earthworms/index.html

Of Worms and Fertilizers

Today I’m going to write about fertilizers and worms. The purpose of this post is not to encourage you to use fertilizers. I agree wholeheartedly with Linda’s post – we don’t need many of the fertilizers which we’re using. Still, it’s important to know the facts about anything that you’re doing (or not doing) to and for your garden, and to do them (or not do them) for the right reasons. With that in mind, I’ve been reading about worms and fertilizers for the last few days and wanted to let all of you know the basics of what I’ve been reading, because it is somewhat contrary to what many gardeners believe.

Before we begin let’s get one thing straight — worms are basically good for your garden and your plants in general. We like them!

Over the years I’ve heard all kinds of comments about how inorganic fertilizer is bad because it kills worms or drives them away. For the most part I’ve just accepted these claims as generally true because it seemed to make sense and I didn’t have a reason to study it further (I don’t write about worms much, and I’ve never spent any time doing research on them – still, I have to admit that this is no excuse for ignorance). The only contrary words I’d ever heard spoken about the reality of what fertilizers do to worm populations had come from a soil scientist friend of mine who told me, in casual conversation, that he didn’t believe that fertilizers were bad for worms at all, except, perhaps in the very short term if they got some fertilizer directly on them. Rather, he believed that, because fertilizers encouraged the growth of plants, fertilizer use would actually increase worm populations because it would increase their food supply.

After reading through a few papers it looks like my soil scientist friend was right. Here I’m going to summarize my general impressions about these papers into a few sentences – not exactly fair because the relationship between worms and fertilizers isn’t completely straightforward – but hey, this is a blog! Basically, if you add fertilizer of any sort to your soil you will ultimately increase worm populations because you will encourage the growth of more plant material. More plant material, over the course of time, means more organic matter for worms to eat. Generally organic fertilizers seemed to be preferred by worms (probably because they include lots of organic material along with the nutrients which they offer), but overapplication of fertilizer (organic or inorganic) could be bad for worm populations, at least in the short term.

So, in a nutshell, judicious fertilizer use shouldn’t affect worm populations negatively. Still, why add fertilizer at all if you can avoid it? Mulch and compost – worms will definitely enjoy that!