Soil improvement and composition

Last updated : 15-03-2013 [First published 10-03-2008]
The worms have now settled down into their new home (with the aid of imported soil) and generally stopped committing suicide, which is excellent. As per instructions however, they aren’t getting too much to eat from my kitchen scraps just yet. But ultimately, the idea is that they create lovely rich compost for my plants. All this hassle just for some soil I hear you ask? Oh yes. “A true gardener does not tend the plants, he tends the soil.”

Soil is an underated and forgotten commodity, but as Doran and Parkin say, “the thin layer of soil on the surface of the earth represents the difference between survial and extinction for most terrestrial life”. The quality of the soil dictates the plant growth in virtually all environments. Soil is the habitat for millions of organisms, nature’s recycler, the medium for plant and therefore animal, growth, an agent of landscape change and a store of history. It’s a big deal.

Pedology (the study of soils) links the lithosphere (earth’s core/crust) biosphere, atmosphere and hydrosphere. Only 5% of soil is organic matter. Of the rest, 25% is air, 45% is minerals and 25% is water. The parent material is usually the rock which makes up most of the unconstitued material just above the bed rock and under the top soil. In between the top soil and the bedrock you can sometimes get many layers (horizons) of different soil.

Soil is classified according to it’s composition in terms of loam, clay and sand. However it is not homogeneous over space or time. Soil can be ‘improved’ for the growing of plants by taking it closer to a loam/sand mixture and by the addition of organic material. Hence the wormery.
So next time you walk across the lawn, think about that soil…..
References:
Doran and Parkin, In Holden, J. Ed. (2005) An introduction to Physical Geography and the Environment. First edition. Harlow.
Fitzpatrick, E.A. (1983) Soils: Their Formation, Classification and Distribution. First Ed. Harlow.
Avery, B.W. (1990) Soils of the British Isles. CAB International. Wallingford.

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