Lesson 60: Plants, Soil, and Erosion
Soil contains mineral particles, organic matter, air, and water. This lesson connects soil composition with plant growth and examines how roots and plant cover affect erosion.
Key Ideas
- Soil contains tiny pieces of rock, decayed material, living things, air, and water.
- Decayed plant and animal material helps soil hold water and nutrients that plants need.
- Roots help hold soil in place. Leaves and other plant material soften the impact of rain and slow water flowing over the ground.
- Plants often reduce erosion, the movement of soil or rock. Rain, wind, slope, and the condition of the ground also affect how much soil moves.
Vocabulary
- Soil: Material at Earth’s surface containing rock particles, decayed material, living things, air, and water.
- Humus: Well-decayed plant and animal material in soil that helps it hold water and nutrients.
- Erosion: Soil or rock being carried away by water, wind, ice, or gravity.
- Weathering: Rock breaking down into smaller pieces or changing chemically, without being carried away.
Discussion Questions
- Farmers sometimes plant a cover crop over a field between growing seasons instead of leaving it bare. What is that likely protecting against?
- Topsoil can form much more slowly than it erodes, and formation rates vary widely. What does that suggest about caring for it?
- Terraced hillsides, flat steps cut into a slope, are used in farming around the world. How might terracing reduce erosion compared to farming straight up a slope?
Supplies
- Two cups of the same soil, a handful of grass or a small rooted plant, a bowl, and water