It’s almost time to sow seeds for your fall crop! My friend Renee Shepherd has a seed company, Renee’s Garden, and a great Web site. Her seed packets are the most informative in the industry, and pretty, too. You can read all about it at www.reneesgarden.com/articles/second_season.html.

For those who missed my Master Gardener Workshop this morning at the farm (the subject was healthy soil, upon which we all depend) here’s a shortened version of what I covered. As always, I welcome any questions you may have.

Good soil is full of life, critters from as big as an earthworm to so small you need a really good microscope to see them. All these forms of life eat, predate on each other, reproduce, excrete, and die. Every stage of their lives is important to the creation of good soil.

Everyone – not just vegetarians – depends for their life on green leaves. Whether we eat them directly, or eat animals that feed on plant products, we cannot survive without plants. (We cannot live without insects, either. One of the great ironies is that we cannot live without them, but they could live perfectly well without us.)

The leaves of plants perform a scientific miracle called photosynthesis. Leaves use sunlight to turn carbon dioxide and water into oxygen and carbohydrates, which charges the roots with energy.

If roots live in healthy soil, they transform this energy into new roots. And just behind the growing tip of every tiny root is where life and death decisions are made.  This area of the root has microscopic hairs that seek out and absorb soil nutrients. Root hairs “steer” the root to where they find the richest supply of nutrients. That’s why roots zigzag all over the place.

As gardeners, we tend to think our primary job is to care for plants. Actually, that is our secondary role. What we have to focus on is the soil. If we help create healthy soil, our plants will thrive without much more help from us. But before we can do that, we need to understand what soil is and how it behaves.

Soil is made up of three sizes of particles, plus organic matter. We are fortunate at EECO Farm, because our soil is what’s called a silt loam. It is the best soil in the world. Some other soils are as good, but none is better.

Silt loam contains roughly equal parts of sand and silt, with a much smaller amount of clay mixed in. The sand allows good drainage, the small particles of silt help soil hold water and nutrients, and the clay holds everything together in a nice loamy mass that all gardeners crave.

The organic matter – compost, plus dead plant, animal, and insect matter – is ideally about 5 percent of the soil. Our soil at the farm has 4.8 percent, which is enviable. If we keep adding compost, we might get even better than 5 percent, which would be great!

Life in the soil is what makes things happen. Soil contains lots of different microbes, including bacteria, along with fungi and many insects. While a few of these life forms can be harmful to plants, most are beneficial. Indeed, plants cannot survive without them. They – and the roots of plants – interact freely and constantly.

For example, mycelium is a type of fungus that lives in the soil. It creates millions of microscopically-small threads, like an underground spider’s web. Some of these threads actually enter plant roots, where there is a trade-off. The roots give the mycelium threads energy, and the mycelium gives the roots nutrients from the soil.

Bacteria do lots of good things in soil. Some turn raw nitrogen into a form called nitrate that is available to plants. Some help organic matter decompose, which frees-up plant nutrients, holds water, and helps feed the rest of the soil population. There are from 100 million to three billion bacteria in one gram of soil. (A gram is about 1/30^th of an ounce).

Lots of insect species live in the soil, from tiny mites to relatively huge earthworms. Nematodes (most are good, a few are bad) are like small wiry worms – the biggest is about ¼ inch long. Springtails, which look like microscopic dinosaurs, are (like earthworms, some beetles, millipedes, and woodlice) consumers of decaying matter in the soil. They are themselves eaten by larger life forms. There are about 100,000 springtails in a cubic meter of topsoil.

Insect activity in the soil moves nutrients around. And when insects excrete or die those nutrients become available to plants. It’s a tough environment, because all soil life is constantly eating other life forms, or being eaten. Because of this, they are all dependent on each other. If a synthetic insecticide kills off a whole slew of life forms, the soil food web collapses.

What happens then is that the soil is no longer able to support healthy plants. Left alone, the soil will slowly heal itself as soil life returns. At the farm, we have given it some help by adding tons of compost, but we need to remember that repeated rototilling wreaks havoc on the soil food web. Imagine a block-wide bulldozer crashing through a city, squashing everything and everyone in its path. That’s what a rototiller is like to the critters that live in the soil, upon which the health of our plants – and, ultimately, ourselves – depends.

Our main job as gardeners and farmers is to care for the soil. If we do that, the soil will care for our plants.