World Soil Day is commemorated every December 5th, so this week, Tidbits has all the dirt on…what else? Dirt! Dive in and get your hands dirty with these remarkable facts about dirt.
- Is there a difference between dirt and soil? Scientists say yes, that dirt is an inorganic mix of broken rocks, minerals like iron, calcium, and magnesium, and matter from living things that have died. Soil, the more scientific name, is dirt plus water, along with organic material, a living ecosystem of about 45% minerals, 25% water, 25% air, and 5% organic matter. Those percentages can vary widely based on different types of soil and the location.
- There are three main types of soil. Sandy soil has larger particles, but has fewer nutrients, and drains well. Clay soil’s smaller particles retain water, but it’s heavier as a result. Loamy soil is a mixture of sand, silt, and clay, and is the best for plant growth.
- Soil is so packed with organisms that just one tablespoon has more microorganisms in it than there are people on Earth, including bacteria, fungi, protozoa, and nematodes. Just a teaspoon of soil contains between 100 million to 1 billion bacteria, as many as 75,000 species. There can be 25,000 species of fungi, 1,000 species of protozoa and hundreds of nematodes species. The top six inches of one acre of soil contain as much as 20,000 lbs. of living matter.
- Soil erosion occurs at a rate up to 40 times faster than the rate of soil formation. A minimum of 500 years is required to form an inch of topsoil, formed through the process of weathering, the process of breaking down rocks and minerals through physical, chemical, and biological processes.
• In the U.S., the most extensive type of soil is prairie soil, covering 21% of America’s land mass. Prairie soil is officially known as Mollisol, characterized by a considerable amount of humus on its uppermost layer, formed under grass vegetation.
- Not all soil is brown! Mineral content, organic matter, and chemicals can give dirt a wide variety of colors from black to red to white and even pink and blue. Iron gives dirt a reddish hue. Blue soil found in New England is a silty soil from which iron has been leached. Pink soil is the result of different organic compounds interacting with clay.
• Earthworms love soil! There can be upwards of 1.4 million worms in just one acre of farmland. They love it because it’s packed with nutrients from decaying plants and animals. As they munch on the matter, they break it down even further, enriching the soil for better plant growth.
- The taste of wine can actually be influenced by the composition and characteristics of the soil where grapevines are grown. Fossilized creatures such as oysters whose cells have broken down in the soil give wine a unique taste, as do grapes grown in white clay soil with a layer of limestone. The soil affects the amount of water traveling to the roots, shaping the ripening process.
- Soil isn’t just for growing things – some cultures consider soil sacred and use it in rituals that symbolize fertility, purity, and the cycle of life.
