Download Rocks: Different Soils

Rocks: Different Soils
Objectives:
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Recognise that soils are made from rocks and organic matter.
Plenary
What can you find beneath our feet? Pupils should draw quick pictures of what the ground
may look like deep underneath the grass. They may include soil, rocks, fossils, skeletons,
treasure, mines, caves or underground trains.
What is soil made out of?
Take the pupils outside to collect some soil. If possible include worms or other living things.
Put the soil samples in plastic or glass beakers and take them inside. Pupils should look
carefully at the soil and see what is inside. They are likely to be able to identify rocks and
dead vegetation.
Explain that soil is made up of dead plants and animals and their products (organic matter),
tiny pieces of rock, water and air. The soft ‘muddy’ part of the soil is made up of sand, silt
and clay.
Pupils must note:
Soil is made up of rocks, water, air and organic matter.
The organic matter does not look like plants and animals for long; the bodies decompose and
enrich the soil, providing plants with food.
Different types of soil
Show the pupils a soil map of the UK. Pupils should see that different parts of the country
have different types of soil. Perhaps they have heard their parents complaining that it is
difficult to grow certain flowers in the local soil. Different plants grow better in different
types of soil; clay soil is good for hydrangeas, chalky soil is good for geraniums and sandy
soil is good for rhododendrons.
EXPERIMENT: Provide the pupils with samples of peat and sandy, clay and chalky soil,
labelled mystreriously as Soil A, Soil B, Soil C and Soil D. Pupils should examine the soils
and write down a sentence about the appearance of Soils A-D. What colour are they? Are
they wet or dry? Are they fine or lumpy? Are they crumbly or smooth? Encourage pupils to
touch and squeeze the soil.
Next, pupils will test how well the soils hold water. They will need measuring beakers,
funnels and filter paper. Pupils should place the filter paper in the top of the funnel and then
fill it to the brim with soil. They should then pour a small cup of water onto the soil and
measure how much water is collected from the end of the funnel.
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Pupils may want to consider why it is important to always pour the same amount of water
onto the soils and which soil holds water best – is it the one from which most water is
collected or the one from which least water is collected?
Pupils should write down how much water is collected from each funnel.
Provide the pupils with the following descriptions of soils:
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Peat is dark, crumbly and feels dank. It retains a lot of water.
Clay soil is slightly orange and holds its shape when squeezed. When water is poured
on it, it does not drain through and instead stays on top.
Chalky soil is light coloured, dry and rocky. It does not hold water well.
Sandy soil is slightly yellow and feels dry and fine. It does not hold water well.
Can the pupils match their mystery soils with the soil types?
Pupils may note:
There are types of soils with different properties, including clay, chalky and sandy soil.
Possible extra-curricular questions
Why is there different soil in different parts of the country?
Soil is made up of rocks and organic matter, so the type of ‘parent rock’ and the type of
plants and animals in an area affect the composition of local soil. The climate also affects the
soil; in warmer regions, soil is often sandy and barren because organic material breaks
down quickly while in cooler regions, soil is often peaty and rich in nutrients because organic
material breaks down slowly.
How do animals decompose?
Dead animals decompose when they are consumed by insects and their larvae (such as flies
and maggots), fungi, bacteria and other microorganisms; these are called decomposers. The
decomposers take nutrients from the body and produce their own waste, which causes dead
things to have that ‘rotting meat’ smell. Eventually the body is reduced to nutrients in the
soil, which help plants to grow.
What is underneath the soil?
Underneath the first layer of soil we find further layers of soil, which we can describe with a
‘soil profile’ or ‘soil horizon’. Beneath the soil is the crust of the Earth, which is made up of
different types of rock. Under the crust is the thick mantle, made up of solid rock which shifts
over millions of years. Beneath the mantle is the core, a hot ball of molten nickel and iron.
Why do farmers like putting poo on the ground?
Manure is a type of fertiliser made up of organic matter (dung). It helps to enrich the soil by
provides nutrients such as nitrogen so that crops can grow in exhausted soil.
© Education Umbrella 2015