Living Soil

This unseen underground community is key to the vitality and fruitfulness of our gardens.

By Elaine Ingham, Ph.D., with Amanda Kimble-Evans

Photography by Calvin Dolley


learn what's in your soilNematodes suffer from a bit of bad press. Most people have only heard of root-feeding nematodes and therefore think all nematodes are bad. But many—the majority, in fact—of these small wormlike creatures are a boon to the garden. Beneficial nematodes help protect roots from disease, help build soil structure, and release nutrients in plant-available, soluble forms, right in the root system.

Microarthropods are an assortment of very tiny organisms that include soil mites, springtails, and soil-dwelling insects. There are many different kinds of these critters, but, in general, their function is to eat fungi, or each other, and release nutrients in a plant-available form. And while they are doing that, they also build structure in the soil.

Like so many things in life, the secret is balance. We need members from each of these groups of organisms in our soil working in concert with each other and the plants they feed. To a large extent, plants control and select for the growth of the microorganisms they need.

But gardening and farming that relies on heavy doses of synthetic chemicals and fertilizers destroys beneficial life in the soil, leaving plants without this important support system. Chemically maintained soils have been reduced to dirt over the course of a half-century, with little or no beneficial life to combat disease organisms or insect pests, and nothing left in the soil to cycle nutrients.

The best way to obtain and nourish the full set of life-sustaining microbes is by adding locally made compost. Both worm composting and thermal composting provide a great diversity of beneficial organisms. In worm compost, the worms consume the pathogens and pests. Thermal composting, also called hot composting, means the pile reaches and maintains a temperature high enough to kill weed seeds, pathogens, and pests. In both cases, the beneficial organisms thrive and help maintain the aerobic conditions of the compost when it is applied to the garden.

Good compost will then replace the life—and the foods that feed that life—currently missing from many gardens, and will turn that dirt back into living soil.