There’s a fascinating and complex ecosystem in garden soil. An interdependent host of bacteria, fungi, crustaceans, earthworms, insects, and other organisms not only support each other, but all plant life as well. It’s called the soil food web.
Every part of the soil food web fits together like a jigsaw puzzle. Bacteria, fungi, earthworms, and small nematodes (a kind of worm) feed on decomposing organic matter and plant root exudates; protozoa feed on bacteria; arthropods and nematodes feed on fungi; the nematodes also feed on protozoa; larger arthropods feed on smaller arthropods and small nematodes; and birds and mammals feed on the arthropods. The birds and mammals excrete the waste back into the soil as manure, which breaks down into organic matter, and the cycle begins again.
And while all of this moving about, eating, and excreting happens, pockets are created in the soil through which water and air move, transporting the nutrients which nourish plant roots. It’s a remarkably interdependent system, and if you remove or diminish just one part of the soil food web, the other parts suffer. As with any form of life, if a food source disappears, the life form moves on, a consequence which ripples through the food chain.
In soils bathed for years in chemical applications of fertilizers, fungicides, and insecticides, life in the soil food web is reduced considerably. In fact, bacteria and fungi plummet and earthworms seek food in deeper parts of the garden, ignoring the topsoil. Plants become totally dependent on synthetic chemicals.
Yet remarkably, soil which is left to its own devices eventually finds the necessary balance with little intervention from humans. Look at what happens to even the worst of urban lots left alone to be reclaimed by nature – after only a few seasons, seeds germinate, plants root and life resumes.
The concept of the soil food web can seem daunting to those who have never gardened, or those who are transitioning to organic gardening. But all that’s really required to restore the soil food web’s balance is a steady diet of compost, which is eventually broken down into the necessary components to sustain life.
Naturally, if one wants to grow magnificent vegetables, fruit, and flowers, some fine tuning of the soil is required. Indoors, this balance can be difficult to achieve by novices, as the gardener can’t take full advantage of the natural ecosystem. Light is controlled, water and heat are controlled, and insect life is minimized.
Outdoors however, heat, cold, water and light stimulate the soil food web and kick it into high gear when enough organic material is present. When the balance is arrived at, plant maintenance drops considerably, and the plants develop a deeper root system which shields them from the harmful effects of drought.
The secret then to bountiful life in garden soil is simple: regular feedings of compost. Store-bought organic fertilizers aren’t necessary (unless you know for certain your soil is deeply deprived of an element), and insecticides and other controls are rarely if ever needed. Replenish the soil with that which came from the soil. It’s as food was grown for 10,000 years before the industrial age of agriculture.
Todd Heft is an author and organic gardener who writes and gardens in Bethlehem, Pennsylvania, USA. His first book is called, Homegrown Tomatoes: the step-by-step guide to growing delicious, organic tomatoes in your garden.