What Is Soil? Is It Just Dirt?
Or Is It the Source of Life?

To some people, soil is what their grass grows on. Some people refer to it in a derogatory fashion, as in "they're dirt poor."

Soil, good soil, is the basis for much of the world's wealth.

Without soils, we'd have no plant crops, and we'd have no animal products.

Without good soils, billions of people would starve.

And yet we treat our soils as though they were lifeless dirt.

And much of commercial agriculture is turning our soils into lifeless dirt.

What Makes Soil So Important?

Soil is what holds plants up so they don't fall over. Yes, any old dirt can perform this task, if the plant will grow in it.

The life in each inch of your garden's soils hold millions of organisms, each of which goes about its life, which results in nutrients for plants to use to grow.

Good soils, soils full of humus, absorb and hold rainwater and meltwater (from snow and ice). Plants can use that stored water when they're thirsty. Rain and snow soaking into the ground also helps prevent flooding.

Almost all fresh water travels over or through soil before entering our rivers, lakes, and aquifers. However, plants remove 400 to 2,000 pounds of water from the soil for every 2 pounds of plant material produced.

Soil is alive. There are lots of creatures that live there. A single shovelful can contain more species of organisms than live aboveground in the entire Amazon rain forest. One cup of soil may hold as many bacteria as there are people on Earth.

The weight of just the bacteria in 1 acre can equal the weight of one or two cows. A teaspoonful of forest soil may hold more than 10 miles of fungi.

Almost all the food we eat, fiber (material) for the clothes we wear, and lumber for the houses we live in starts in the soil.

About 85% of carbon dioxide in our atmosphere comes from microorganisms feeding on organic matter. So it's a good thing that mature trees can have as many as 5 million active root tips extracting nutrients from the soil. Those root tips ensure that trees remove tons of carbon dioxide from the air and replace it with oxygen.

What Is the Soil Food Web?

The soil food web is a way of relating soil organisms to each other based on what they eat.

The soil food web starts with organic matter. This could be crop residues, pasture or any plant material in the soil.

Bacteria and fungi consume organic matter, breaking it down in the process. Bacteria and fungi are in turn consumed by nematodes, protozoa, earthworms, collembola and some mite species.

Nematodes and protozoa are consumed by mites. Mites and collembola are eaten by beetles and ants.

This consumption process may sound linear, but researchers have found that it is indeed closer to a web, hence the name soil food web.

Additional Topics About Soil

What We Can Do for Soil Quality

Acid Soil

Alkaline Soil

The Importance of Soil pH

Why a Soil Test?

Taking a Soil Test

State and Local Soil Testing Labs

Some of the facts that answer the question What Is Soil? were provided by the USDA (United States Department of Agriculture).