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Soil Erosion Bottle

Don’t get washed away by this gritty activity!

Australian Curriculum links

  • Science > Earth and space sciences > Year 4 > ACSSU075

You’ll need

  • 3 x clear large plastic soft drink bottles
  • 3 x clear plastic cups or small PET bottles
  • Stanley knife
  • String
  • Loose-weave fabric, such as old stockings or flyscreen
  • Rubber bands
  • Potting mix or soil
  • Seeds or seedlings
  • Leaf litter or straw
  • Plasticine
  • Jug

Try this

  1. Lay the bottles on their side and carefully cut a large, rectangular hole along the side of each bottle. You might need some help with this from an adult.
  2. Wrap the fabric over the neck of the bottle and secure with a rubber band.
  3. Fill the first bottle so it is ⅔ full of potting mix. Plant seeds or seedlings. You might need to start this a few weeks before your other bottles if you are using seeds, as established roots in the soil are key to this experiment.
  4. Fill the second bottle ⅔ full of potting mix and cover with leaf litter or straw.
  5. Fill the final bottle ⅔ full of potting mix.
  6. Make two holes in your plastic cups or small bottles.
  7. Tie string through these holes and make a loop to hang over the top of your bottles.
  8. Place the bottles so that the necks are at the edge of a table or bench and the cups hang freely. You might need to add buckets underneath to catch any overflow, or you could perform the rest of this activity outside.
  9. Raise the base of the bottle so that the nozzle is angled downwards. Secure with plasticine.
  10. Water each bottle so that water flows through the nozzle into the hanging cups.
  11. Observe the difference in the water flowing out of the cups.

Further investigation

  • Try using different plants.
  • What happens if you use different soils?
  • Try using different materials on top of the potting mix, such as shredded paper or pine needles.
  • Try planting seeds or seedlings in horizontal and verticals rows. What is the difference in the run-off?

What’s happening?

Soil erosion occurs when water or wind move across soil, carrying soil particles away. When a lot of soil is moved, this can create gullies or sheets of erosion. Soil erosion takes the top, productive layer of the soil, which contains all the nutrients. Human activities have accelerated erosion, greatly affecting the fertility of the soil. Ensuring soil is not left bare and that plant rows are perpendicular to the direction of water flow help protect soil from the effect of running water.

Real world links

Erosion isn’t all bad. It is responsible for some stunning landscapes. The Colorado River has eroded the Grand Canyon over millions of years. In Australia, the coastal erosion is responsible for rock formations, such as the Twelve Apostles in south-western Victoria.