We need these Soil Tillers by Cleeland Bean
The role of the earthworm in maintaining soil structure and fertility has been challenged by those who believe there is no agricultural or horticultural problem that cannot be solved chemically. This underrates the value of an animal which may be the best ally of the farmer and gardener and which is sensitive to many agrochemicals and modern techniques of husbandry.
One particular animal which receives rough treatment from farmers and gardeners is the common earthworm, and in terms of conservation or ecology it would seem that we should be paying closer attention to its important function as a useful soil turner on agricultural land. The amazing actions of Lumbricus terrestris when observed among fertile earth layers have been demonstrated by British and American biologists who know that a lack of worms will produce hard, unmanageable ground blankets where good growing conditions are absent.
But long ago Darwin had calculated that on an acre of land worms will pass 10 tons of soil through their bodies every year. Professor Brian Hackett who leads a research team at Newcastleupon-Tyne University points out that on an acre of fine arable land the total weight of worms below ground will be greater than the number of cows above it. He recognises how earthworms form vital links in a balance of nature where strong bonds exist between the humblest animals and their micro-habitats.
Worms share an environment with many other soil-dwelling creatures including insect larvae, spiders, centipedes, woodlice, springtails, mites, false scorpions, millipedes, harvestmen and beetles etc. Each species reacts upon the other, and more so when earthworms provide them with suitable hiding places in fertile soil layers made rich by leaf mould. Decaying leaves attract many worms whose underground tunnels on
an acre of land can cover 75,000 miles in a year.
During the same period investigations have shown that the animals will cast up to the surface anything from 20 to 400 tons of rich soil. Their burrows enable life-giving air, water and mineral supplies, to reach deep underground where plant roots, tree roots, seeds and useful soil bacteria require nourishing food articles. I t may surprise us to know that we have at least 37 earthworm species in the British Isles, and they are all useful for producing healthy plants.
Studies show that these denizens can push aside stones weighing up to 2 ounces, and this is more than twelve times the weight of an average worm. The depth at which worms have been found is another aspect of soil aeration in relation to seed development and the root growth of trees and plants. Some specimens can thrive at levels as deep as 25 feet, while many others will be found at the 8-foot mark. Depth distribution depends of course upon the type of soil, and on newly tilled land Russian scientists find that worms will be quite numerous within the 20-inch depth level. Smaller specimens occur nearer the surface with an earth layer of 8 to 12 inches above them.
But as might be expected worms in general are not so numerous in sandy or clayey land formations; here too they will be much smaller. However, it is possible to attract earthworms by treating poorer soils with suitable vegetable humus or organic materials. Some people quicken this process by mixing liberal quantities of manure, hay, dead leaves, kitchen scraps and hedge clippings, etc. with the top earth layers. Other gardeners have added lawn cuttings, decayed fruit, eggshells, pea pods, meal and even old newspapers.
Such work would be fully supported by the Soil Association whose members warn us about the menacing effects of soil erosion which could become widespread in Britain if we are not more careful concerning our efforts to squeeze the last ounce of goodness from agricultural land by the wholesale use of toxic chemicals. We must realise that earth is a living substance, and that an indiscriminate chemical spraying policy cannot be expected to produce good results.
Under such conditions our useful earthworm populations can be wiped out, and sterile soil layers will upset the balance of nature which ought to exist between bacteria, insect species, seed development and water action. Al though the ancient Egyptians did not have the benefit of modern scientific knowledge we must give them credit for acknowledging the value of earthworms. Indeed it was Cleopatra who brought in laws or regulations whereby worms were to be protected as useful tillers of the fruitful Nile Valley.
Enlightened farmers and gardeners will agree that Cleopatra had the right idea, especially when they realise how worms can produce better crop, grass and fruit yields. For example, well tested land experiments in California have shown that when the ground enclosing orange groves was liberally supplied by earthworms the trees gave bigger and better fruit compared with other groves where worms were less plentiful. This reaction is what we would expect, and it backs up the US Department of Agriculture whose field biologists have found that on an acre of good land earthworms can convert 700 pounds of digested soil into surface castings each day. Better still is the