Homes & gardens: The earth moved

Where would we be without worms? It's a question I often ask myself as I sit on my allotment bench swigging from my Thermos, surveying the thousands of small stones these wriggly critters have dragged up to the surface overnight. It's a question that struck Charles Darwin too, but being the 19th century's greatest scientist, he thought about it more seriously than most. So seriously, in fact, that he spent his declining years breathing tobacco smoke over them and even, famously, playing them the piano in order to find out whether they were sensitive to vibration (they were).

Had Darwin gone gaga? Not a bit. In 1881 he published his observations in The Formation of Vegetable Mould, Through the Action of Worms, With Observations on Their Habits. It became a bestseller, and its conclusions are as relevant today as they were more than a century ago.

The American writer Amy Stewart is someone else who's been bitten by the earthworm bug, and her book, The Earth Moved (Frances Lincoln, pounds 14.99), is published later this week. What sparked her interest was a worm bin, those plastic tubs which swallow your kitchen scraps and (at least in theory) regurgitate liquid fertiliser and rich, dark compost for your garden. In the spirit of other popular-science writers such as Bill Bryson and Jared Diamond, Stewart has burrowed, ahem, deep into her subject and unearthed some fascinating stuff. Did you know, for instance, that one endangered Australian worm can stretch to 10 feet? Or that there are bright- blue worms sprinkled with yellow spots in the Philippines?

Worms, as we know, are the gardener's (and the farmer's) friend. They aerate the soil, break down organic matter and keep the earth in constant (though admittedly rather ponderous) motion. As Darwin pointed out, "The plough is one of the most ancient and most valuable of man's inventions; but long before it existed the land was in fact regularly ploughed by earth-worms." Most people have taken Darwin's words as a typically engaging metaphor, but recently some ecologists have begun taking them literally. The result is the so-called "no-till movement", whose principal tenet is that the less the earth is disturbed, the greater the worm population, and the higher the number of worms the better the condition of the soil. For anyone who, like me, has done their back in digging, it's an appealing idea, but no-till has yet to be widely adopted. Perhaps that's hardly surprising as most gardening manuals still advocate deep digging to improve soil quality - despite mounting evidence that undisturbed earth is up to 60 per cent more productive.

So it seems that we should all be taking more care of our earthworms. If only they were a bit more cute and cuddly. As Amy Stewart says, "Are we so focused on image, on appearance, that we can only love the prettiest inhabitants of the garden and neglect the slimy but hardworking earthworm?"

After reading The Formation of Vegetable Mould, Darwin's friend Joseph Hooker wrote: "I must own I had always looked on worms as amongst the most helpless and unintelligent members of the creation; and am amazed to find that they have a domestic life and public duties!" By the end of The Earth Moved, you may be inclined to agree.