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The Federation of Heathfields Infant and Wilnecote Junior SchoolsACHIEVING AND GROWING TOGETHER WITH PRIDE

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Activity 4 - Soil investigation

Soil analysis

 

This is one of the experiments which we would have tried in school whilst studying rivers.

 

As a river flows, it picks up rocks, soil and sand along with other debris as it flows along.

 

Soil is the surface skin over the Earth’s landscape. It supports an important food web and is one of our most important natural resources.

 

Soils consist of mineral grains that come from rock sediments, organic matter, water, air and a huge number of organisms. Depending on the landscape, the quantity of each component varies and changes over time.

 

Soil can be divided into three layers or horizons: topsoil, subsoil and parent material (bedrock).

 

There are typically three soil particles: sand, silt and clay. They come from the rocky parent material and determine the make up and texture of the soil. Soils with lots of sand in are sandy soils, and so on.

 

Each soil particle is a different size – sand is largest and clay is smallest. The size of a particle affects how much water a soil can retain. Clay soils hold water and make land boggy, whereas water passes through sandy soils quickly.

 

We can find out how much of each particle and organic matter is in a soil sample by mixing it with water and leaving it to settle. After a minimum of three hours, the soil separates into layers according to the weight of the particles. Rock sits at the bottom, then sand, silt and clay, with organic matter on top. The deepest layer tells us the texture of the soil.

 

Look at the instruction sheet and talk with your grown up abot the process of the experiment. Think about the locations they could compare. Suggestions might include soil from the top and bottom of a hill, home and school, grassy and wooded areas, or natural soil and shop-bought compost.

 

Collect and label their samples clearly so that they don’t get mixed up.

 

Important
Discuss potential hazards found in soil, including broken glass and harmful bacteria. Make sure that you wash your hands thoroughly.

 

 

If this isn't clear, here's a list of what to do;

 

  1. Collect a soil sample from two contrasting places.
  2. Compare and record similarities and differences between the samples. Make a note of colour, texture, moisture, smell and objects in the soil.
  3. Place the samples into separate jars until they are half full and take a photo of both.
  4. Fill each jar with water from the tap. You may need to top them up as the soil releases air bubbles.
  5. Use a spoon to give the samples a good mix. Get right to the bottom of the jar. Leave the jars to settle overnight.
  6. The next day, examine your samples and look at any layers that have formed. Look closely as some may be very thin!
  7. Measure and record the depth of each layer in both jars with a ruler.
  8. Record any other differences, such as colour or smell.

 

After the experiment

 

Here are some questions to think about;

  1. What is soil?
  2. Why did layers form in your samples?
  3. Can you describe the texture of the soil you found in your sample locations? Explain the similarities or differences between the two samples?
  4. Why is soil important?
  5. How easy was it to see and identify the different layers in the jars? What might have made it easier?
  6. What other mixtures could you investigate using the same method?

Here is a PDF version of the instruction sheet - click the icon to view it.

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