Soil! What IS SOIL? Here's the definition given in my Master Gardener Handbook. It's pretty all encompassing and we know that it's RIGHT! If you visit the link I provided above, you'll see a longer explanation. In either case, soil is critical to the gardening process.
"Soil is formed when rock (parent material) is broken down by climate and vegetation over a period of time. Soil is weathered rock fragments and decaying remains of plants and animals (organic matter). It contains varying amounts of air, water, and micro-organisms. It furnishes mechanical support and nutrients for growing plants."
In other words, if you're a gardener, you need soil!