Tuesday 18th September 2018 – Dr Frank Ashwood – Earthworms
Earthworms are recognised ecosystem engineers, proving invaluable services to humanity and transforming and improving the soil habitat for other organisms. Most naturalists are aware of their fundamental ecological importance, but few have detailed knowledge of any of our 30 or so native British species. Frank’s PhD was entitled ‘Woodland Restoration on Landfill Sites: Earthworm Activity and Ecosystem Service Provision’. He is a soil ecologist working within Forest Research’s soil sustainability research group. Here Frank will describe earthworms’ behind-the-scenes work, which underlies the productivity and diversity of the natural systems we see every day.
Brilliant talk last night at the first Bath Nats indoor meeting of the season. Who knew, for instance, how many different species there are, or how to tell the head from the tail and even how mature they might be? Who knew exactly how they move, and that they achieve this with tiny – almost invisible bony ‘feet’. Sea fishermen would know how fiercely a lugworm can resist being pulled out of the sand, but I never knew the mechanism by which it achieves this strength, (the ‘bony’ feet are sharp, like teeth). There was so much to take in, but for me, the take-away point was that digging – i.e. disrupting the upper soil layer does the earthworms no good at all. I’ve always wondered if the “no-dig” school had any scientific underpinning at all, but last night we had it in (sorry) spadefuls! Here’s a link to The Earthworm Society of Britain should you be interested in becoming a field recorder or just winning a surprise victory in a pub quiz – https://www.earthwormsoc.org.uk
However, when you’re faced with an allotment that looks like a weed infested field interlaced with an impermeable layer of old plastic carpet, there doesn’t seem much future in covering it with more black plastic and hoping when you come back in six months, you’ll be digging in a foot of weed free loam. That’s to say, digging is the only show in town. Bindweed, couch grass and creeping buttercup – to name but three – laugh at black plastic and regard weed control mat as a kind of play pen. At which point many new allotmenteers either give up altogether or turn to glyphosate to do the work for them.
So my second take home point from the talk is that if digging is disruptive to worms, glyphosate and most other chemicals are downright poisonous. As always the point is not to allow the perfect to drive out the good, and the fact is that digging is the hard but necessary first step in creating good soil on the allotment. Once you’ve got the upper hand, which might take a couple of seasons of weeding and hoeing, but during which you’ll still be able to grow things; then you can ease up on the digging and use deep mulches to feed the worms and the soil at the same time.
As it happens we were moving in the ‘no-dig’ direction in any case and I’ve already started a trial and I’m breaking at least two of the gardening dogma at once. I’ve sown some very late carrots in two adjoining cold frames – one lot straight into Sylva Grow compost and the other into composted manure – so that’s apparently certain to result in forked roots according to the rules. The other broken rule is that I didn’t dig the underlying soil at all and so the compost is lying on undug (but weed free) ground. We’ll see the results of my trial in the spring and I’ll post about it good or bad.
The hole in the corner of the frame was almost certainly made by a rat. They’re ubiquitous in Bath: just one of the things the Council wouldn’t like to be better known!