Background
We are not talking about dirt! Dirt is the stuff that gets under your fingernails or it is the stuff that you wash off the car. Soil supports life.
Under the soil that covers Kansas is a layer of rocks. In some places, the rock is only a few inches down. In other places, it is several feet down. Imagine a bulldozer pushing all that soil off the rocks in an area the size of a football field. Then, put a big drain in it so it would not just fill up with water. Would plants grow on those rocks? No. At least not for a long time. Most plants need soil. If we just left it alone, eventually soil would start to form
there. How would those rocks change into soil?
Bare rock
What is soil?
Soil is a mixture of air, water, organic matter (dead and living organisms) and minerals.
The air is absorbed from the atmosphere above the soil. Water is soaked up when it rains or snows. The organic matter is the dead and living organisms such as the plants, insects, bacteria, fungi, and other organisms. The mineral comes from the rocks as they break down.
What causes the rocks to break down?
This can happen in three ways:
- Physical weathering
- Rocks shrink and swell as the temperature changes. This causes little pieces of the rock to break off and causes the rocks to rub against each other. This friction breaks off little pieces. Also, most rocks can soak up a little bit of water. When they water freezes, it breaks off tiny pieces.
- Chemical weathering
- Minerals of the rock mixes with water, air and other natural chemicals that causes the rock to break down.
- Biological weathering
- This is the breakdown of the rocks by living organisms. Roots can grow into the rock causing tiny pieces to break off. Insects and other animals may dig at the rocks looking for food or a place to hide. This allows more water to get into the rock which can cause more physical and chemical weathering.
- What influences how fast soil can be formed?
CLORPT! It is not really a word; the letters represent the things that affect how fast soil is formed:
- CL = Climate
- Temperature has a big affect on chemical reactions. More rainfall also means more reactions. Big swings in temperature means more freezing and thawing. Climate is all of these things.
- O= Organisms
- The type of organisms that inhabit the area can affect this. The type of burrowing animals, growing plant roots, bacteria, and fungi all can have an effect.
- R = Relief
- Relief is a way of describing the way the land lays. It may be sloped. If it is on a slope, which direction does the slope face and how steep is the slope? This effects the amount of sunlight it gets, which affects the temperature. Also, the amount of the slope determines how fast the water runs off of it.
- P = Parent Material
- The parent material is the rock. Some rocks are harder than others and do not break easily. Some rocks are more porous. This means that it has more holes and will soak up more water.
- T = Time
- How long the rock(s) have been exposed to the elements of nature? The longer they are exposed, the more porous they become. The more porous they become, the faster they break down.