Students build a simple erosion model using soil-filled bottles to investigate how ground cover (grass or mulch) reduces soil erosion compared to bare soil. By simulating rainfall, they observe differences in water clarity and soil loss, linking soil conservation to water quality and agriculture.

1. Cut off one side of three identical plastic bottles.
2. Fill each bottle with soil. In one bottle, plant grass seed or place sod and allow it to establish before the experiment.
3. Add a mulch or dead-leaf cover to the second bottle, leaving the third bottle bare.
4. Suspend the bottles at a 25–40° angle with the spouts facing downward over three clear collection cups. Use blocks, cups, or wire hangers to support them.
5. Simulate rainfall by evenly applying water with a watering can or spray bottle across all three bottles.
6. Collect the runoff water in the cups and compare clarity, turbidity, and sediment content.
7. Observe and record how the soil surfaces change during and after the simulated rain.

Erosion and Soil - funsciencedemos:

Soil erosion demonstration - Milne’s Science Tech:

📄 Build an Erosion Model - Soil Science Society of America: https://www.soils4teachers.org/files/lessons-and-activities/activities/lessonplan-erosion-model.pdf

• Use different types of soil (sand, clay, loam) to compare erosion rates.
• Try steeper or shallower slopes to see how slope angle affects erosion.
• Compare effects of different ground covers, such as straw, leaves, or bark mulch.
• Run repeated rain simulations to test cumulative erosion effects.

• Use scissors or a utility knife carefully; adult supervision may be required.
• Handle soil and mulch with clean hands; wash thoroughly after the activity.
• Dispose of soil and water responsibly, avoiding clogged drains.

• Which soil cover produced the clearest runoff water? (Grass cover usually results in the least turbidity.)
• Why does mulch or vegetation reduce erosion? (It protects the soil surface from rain impact and slows water flow.)
• Why is soil conservation important for farming? (Topsoil contains most nutrients; losing it reduces productivity.)
• How does soil erosion affect rivers and lakes? (Sediment reduces water quality, harming fish, plants, and insects.)
• What actions can gardeners or farmers take to reduce erosion? (No-till farming, planting cover crops, mulching, maintaining grass or plant cover.)