Fun Facts About Garden Soil

Dishing the dirt on the soil beneath your feet.

Clay Soil

Clay Soil

©2008, Dorling Kindersley Limited

2008, Dorling Kindersley Limited

Soils are classified as clay soils, sandy soils, or loamy soils. Clay is nutrient rich, but slow draining. It will hold its shape after being squeezed.

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Most gardeners don’t start out with perfect soil. We usually have to amend it to help our plants grow and take in the nutrients and water they need to produce flowers or food.

But there are some secrets buried under the ground, so to speak. See if you know the real dirt on dirt:

  • It can take a minimum of 500 years to make one inch of topsoil.
  • A tablespoon of soil has more living organisms than there are people on Earth right now.
  • Some of our dirt is stardust, the remains of stars that fall to Earth after they’re caught by gravity, a magnetic force, or some other kind of force field.
  • You can’t see them with the naked eye, but billions of bacteria live in each square yard of dirt. Many help keep the soil healthy and balanced by regulating pH or degrading organic matter.
  • Most of the earthworms that live in our dirt are non-native. If native earthworms existed before the last Ice Age, some ten thousand years ago, we haven’t found signs of them.
  • As earthworms plow through the dirt, they push the soil around and actually eat some of it. Their castings—the stuff they put out—help improve garden soils.
  • Rocks weather and eventually become soil. Clay results when the process stops and a different structure starts to form. If you could spread all the Earth’s clay into one even layer, it would measure one mile thick over the entire planet.
  • Scientists say that hydroponics—gardening in only water and nutrients—can work, but plants don’t reproduce well. They believe that growing in soil is better in the long run.
  • If the structure of your surface soil is good, water will be drawn up out of the ground by capillary action (think, “sucking power”), and your field will be fertile. If your surface soil is poor, underground water can’t drawn up into plant roots, and you’re likely to have a desert.
  • Author William Bryant Logan in his book Dirt: Ecstatic Skin of the Earth says the Earth works like a machine when it comes to making soils. Volcanoes spew materials from the core into the air, where they fall back to the ground. Plants and algae change sunlight and carbon dioxide into food and oxygen, while animals turn the oxygen back into carbon dioxide.
  • The lesson of the Dust Bowl is that we’ve got to replace what’s used up to keep our soils fertile. Just 60 years of cultivation can reduce the organic matter in farmland by one-third.

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