There are many investigations which could be carried on your school site, and a really simple (and sometimes a bit messy) investigation is to discover what type of soil can be found beneath the students feet on their playing fields. This is quite a primitive soil investigation which requires little specialist equipment. We borrowed universal indicator and distilled water from our lovely Science department.
We used this website for inspiration https://www.bitesizedgardening.co.uk/diy-soil-testing-for-soil-type-structure-compaction-ph/how-to-dig-for-victory/#:~:text=Soil%20Testing%3A%20The%20Jam%20Jar%20Test&text=Take%20a%20large%20wide%2Dnecked,the%20bottom%20of%20the%20jar. but there are a wide range of different soil tests that could be carried out.
Equipment you will need:
- Trowels
- Pots or bags to put soil in when you are collecting it (if you are using pots with no lid you may want to take something to cover them with)
- Marker pen
- Jam jars with lids
- Distilled water
- Universal indicator
- Washing up liquid
- Equipment to clean up with afterwards
- Infiltrometer
- Water to pour into the ground
- Recording sheet (I have added a very basic version to the end of this blog)
Methodology
- Choose a number of contrasting sites, for example at my school we used soil by a hedgerow, at the very end of our school field where students aren’t allowed to go and under a tree which is experiencing soil erosion.
- At each site, using a trowel, remove the top layer of vegetation and dig down several inches to gain your sample. Fill your bag or pot with soil and label it with the site number. Replace the top layer of vegetation.
- You could also measure infiltration at each site with an infiltrometer and water. We dug our infiltrometer into the ground and poured in 500ml of water each time and timed it. We used this to consider the quality of the soil and the factors that might impact infiltration around the school site (linked to Water and Carbon A Level topic)
- Take the soil samples back to the classroom.
- Take a small sample of the soil from one site in the palm of your hand and slightly dampen it, then squeeze your hand closed. Does it stay clumped and stuck together – if so it could be a clay soil. Does it fall apart, despite being squeezed – if so it might could be a sandy soil. Record this on your sheet.
- Now take some of that sample and rub it between your thumb and forefinger. Does it feel gritty or smooth? If it feels gritty it could be a sandy soil. If it feels smooth it could be a clay soil. Record this on your sheet.
- In the pot or bag of soil add some distilled water and drop in a few drops of universal indicator, what colour does it go? Record the pH score on your recording sheet.
- Pour all of the soil and water into a jar and add more water to cover the soil. Add a few drops of washing up liquid and put the lid on the jar. Shake the jar and then leave to settle. Over the next 24 hours the different layers of soil will settle. This will enable you to say the types of sediments in your soil. These could then be drawn the next day. We referred to the website above when deciding what type of soil this might be.
- Repeat with your other samples.
- Wash up all of the equipment, ensure the jars are labelled with site numbers.
Why did we carry out this investigation?
We carried out this investigation with our Year 12 A Level Students, but this could be carried out any key stage. Our students study the AQA A Level topic Population and the Environment, part of which covers soil. Whilst students do not need to carry out an investigation it encourages them to think about the type of soil we have here, the properties of soil and how the land use might impact the soil. It also enabled us to evaluate the simple investigation that we did, in preparation for getting them to think about their NEA.
Whilst we were outside I asked lots of questions to get them thinking about the knowledge that they had already gained through their study of the unit, for example: “Why might there be more vegetation here than there?”, “What is impacting the infiltration rate here”, “Why does this soil sample look a different colour to this one”, we also questioned how we might improve the investigation, for example – how many times would we repeat an infiltration test?
This investigation was carried out during a two-hour double lesson and students worked in groups of 3-4 to collect and analyse their samples.
Below is a very simple recording sheet that could be used during this quick investigation.
