I recently tilled most of the raised beds in our garden with a garden digger (the red tool in the middle of the photos).
Even though we have a gasoline-powered tiller, we decided to till manually. It was hard work — to till, I had to lift it vertically as high as possible (the tiller weighs 21 lbs), plunge it into the soil, step onto the crossbar, jump up and down until it went all the way into the the soil, and then step back and pull it to me until it was almost horizontal. Then raise it to vertical, step back six inches, and do it again.
Fortunately, it was a cool day in early March with a steady wind that kept me from overheating (no way I’d do this in the humid Summer). Even with the cool temperatures and the wind, sweat was dripping off my chin. It was very satisfying to get down and dirty. E. F. Schumacher (author of Small Is Beautiful) would have approved.
Why did I do this manually when we have a power tiller?
Biological: The earthworm is essential to composting; the process of converting dead organic matter into rich humus, a medium vital to the growth of healthy plants, and thus ensuring the continuance of the cycle of fertility.
Chemical: As well as dead organic matter, the earthworm also ingests any other soil particles that are small enough (including stones up to one-twentieth of an inch across) into its ‘crop’ wherein minute fragments of grit grind everything into a fine paste which is then digested in the stomach. When the worm excretes this in the form of casts which are deposited on the surface or deeper in the soil, a perfectly balanced selection of minerals and plant nutrients is made available in an accessible form.
Physical: By its burrowing actions the earthworm is of great value in keeping the soil structure open, creating a multitude of channels which allow the processes of both aeration and drainage to occur. Permaculture co-founder Bill Mollison points out that by sliding in their tunnels, earthworms "act as an innumerable army of pistons pumping air in and out of the soils on a 24 hour cycle (more rapidly at night)" (Permaculture- A Designer’s Manual, Tagari Press, 1988)- thus the earthworm not only creates passages for air and water to traverse, but is itself a vital component in the living biosystem that is healthy soil.
Note: The application of chemical fertilizers, sprays and dusts can have a disastrous effect on earthworm populations. Nitrogenous fertilizers tend to create acid conditions, which are fatal to the worms, and often dead specimens are to be found on the surface following the application of substances like DDT, lime sulfur and lead arsenate.
Modern farming ignores the lowly earthworm, depending instead on chemical fertilizers and pesticides to grow the food that most Americans consume. I don’t see how food grown commercially can be as healthful as the organic vegetables we get from our garden. Perhaps the rising price of oil will force large agricultural companies to start taking better care of the soil because the most of the chemical additives are oil-based. Time will tell.