A week ago, I mowed the lawn wearing a T-shirt. It wasn’t so much that the grass needed cutting, although it was green and growing a little. It was just that I wanted to mulch up the stray leaves that had blown in since the previous mowing. As a matter of fact, I didn’t do any leaf-raking at all this year. Instead, I used our mulching mower to cut the leaves right into the lawn.
It’s an experiment aimed at fostering earthworms. I knew upon taking ownership here that our hard-packed dirt needed to be loosened up if we were going to develop a nice, spongy turf, and I imagined that worms could be effective at this. But I didn’t know how to go about obtaining worms. I searched the Web looking for worm suppliers, but also started reading about worms, and began to realize that they probably wouldn’t need to be imported after all. It seemed to be more a matter of just making the yard worm-friendly, and they would find it and multiply.
It turns out that worms eat dead vegetation — especially dead grass and leaves. Worms come to the surface to find this organic matter, then pull it down underground. There it softens, the worms eat it, and they pass it out as worm “castings,” which are among the finest organic fertilizers in the world. A single earthworm can produce 10 pounds of the stuff per year. According to this article from Purdue University, there are three basic levels of worms — the litter-dwellers, shallow soil dwellers, and deep-burrowers:
The deep-burrowers (“nightcrawlers”) build large, vertical, permanent burrows that may extend 5 to 6 feet deep or more. They pull plant residues down into the mouth of their burrow, where the residues soften and can be eaten at a later time. Nightcrawlers construct middens over the mouth of their burrows. Middens are a mixture of plant residues and castings (worm feces) and probably serve as protection as well as a food reserve. Because nightcrawlers require residues at the surface to pull down into their burrows, we do not expect to find any nightcrawlers in fields which routinely leave no surface residue cover (i.e. moldboard-plowed).
So, no food on the surface, no nightcrawlers. All summer, I used the mulching mower to put the clippings right back on the lawn, and over the fall I did the same with the leaves. Gradually, the turf did start to soften up, and I did start to notice worms.
We also want to keep our lawn free of pesticides, herbicides, and chemical fertilizers. The original idea was to avoid polluting Lake Michigan or making our backyard birds sick, but I imagine the worms are better off without the chemicals too. When you think about it, the standard practice of removing natural soil enhancers like clippings and leaves, then replacing that nutrition with chemical supplements, is kind of dippy. My only compromise is Milorganite®, Milwaukee’s own organic nitrogen fertilizer, made from the waste solids of the Milwaukee Metropolitan Sewerage District (yes, I know, but it’s in handy dry pellet form). The history of Milorganite is a fascinating read, and golf courses swear by the stuff. You get lots of green and zero burn, and the worms probably get some random antibiotics and whatnot.
After one full growing season, I still don’t have a full-tilt composting operation. Early on in his Wisconsin Garden Guide, author Jerry Minnich heaps praise upon compost, giving detailed instructions for several methods, and even excerpting a Walt Whitman poem on the subject. So far, I have not built the white picket bin he shows in a photo, and I have not hauled manure to our yard, although friends have offered theirs.
What I have done is add to a pile that began with the chopped leaves of 2005. Over the summer, all of our coffee grounds got mixed in, along with vegetable scraps like potato and carrot peelings, onion skins, dead plants, the sod we removed for flower beds, and even the Halloween pumpkins, cut into small chunks. A little water, a little decomposition, and all of a sudden the pile was crawling with earthworms. Turning it with a pitchfork, I saw worms 8 to 10 inches long and as big around as my pinky. They move fast, and have been converting the pile with surprising speed into a dark, homogeneous matter that looks and smells like rich dirt.
Imagine what I can’t see. Wikipedia’s “earthworm” entry quotes research finding that rich soil can support 432 worms per square meter. At a potential of 10 pounds of castings per worm, that could mean up to two tons of this “perfectly balanced selection of minerals and plant nutrients” being deposited in the top six feet of every square meter of soil, given enough dead vegetation for the worms to eat. Now of course those are idealized numbers and the reality in my yard or yours will be lower, but doesn’t it make you think about the natural systems that were in place long before any tanker trucks full of lawn chemicals started rolling down our neighborhood streets?
Freedom from raking, free waste disposal, free fertilizer, free soil aeration, free food for robins — that’s an amazing return on essentially no investment.