Soil Properties—We Dig Dirt!
This week we had a great time playing with dirt! Scientifically we like to call it soil, not dirt, and the young scientists used their inquisitive minds to examine what exactly is in soil. But first, they learned about the ecological, biological and topological factors that contribute to soil formation over hundreds and thousands of years. For example, many of us know that rocks will eventually erode into tiny pieces that become soil. But others of us might not appreciate the role that microorganisms play in soil formation (they help break down organic material such as leaves and other dead bugs) or that soil contains large amounts of air and water.
We need to protect our soil because its important to every living organism on earth. A healthy soil allows plants to grow, and plants are essential to life along our entire food chain. Soil also helps filter out impurities (acid rain, industrial wastes) before they can reach our water supplies. To illustrate how well soil acts at filtering out impurities we filtered dark colored grape Koolaid through a soil mixture and the students could observe how much paler the resulting filtered Koolaid appeared because the soil literally filtered out some of the color.
Experimentally this week students examined 4 different soils (clay, sand, topsoil and Miracle Gro potting soil). They noticed differences in the soil colors and were able to correlate that color to what is in the soil itself. Dark brown/black soils tend to contain lots of broken down organic material, sandy soils tend to contain many mineral fragments and even parts of shells, and red toned soils might contain high amounts of iron. Students also observed the texture of the soils noting that some soils contain smaller particles than others. Finally, students observed how well soils can hold, or not hold, water. All of these factors (color, texture, water handling ability) are important in determining how healthy a soil might be for growing crops or how productive soil might be in filtering out impurities from water.
Feel free to look more closely at the soil in your own yard now and see what you can find!