Fieldwork involving soils and slopes: KS4

Introductory techniques

The concepts of soils and slopes in geography can be linked to many KS4 topics, such as soil erosion, mass movement, flooding and ecosystems. Even on a relatively gentle slope you can see variation in soil compaction and moisture content. This is a great opportunity for a small-scale investigation giving quantitative measurements and can be used to really focus on justifying sampling strategies and data presentation.

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As a starter students should look at: Sampling – The Basics – Field Studies Council to consider the three main types of sampling strategies and how they might be applied in the context of the aim below.

Teachers need to identify a grassy or bare ground slope in school grounds or nearby that you have permission to investigate and take small soil samples from.

Soil and slopes fieldwork

Aim: To investigate the effect of slope on soil characteristics.

Equipment:

tape measures
knitting needle
a plastic or cardboard tube – think wrapping paper tube or poster tube*
soil augers or clean trowels
PH test kit (either simple test strips and deionised water or use Barium Sulphate and Universal Indicator solution, the method is here: Soil – Field Studies Council)
collection tubes or pots
marker pen to label soil samples
access to a microwave or oven.
30cm ruler.

*Not compulsory

Using the thinking about sampling strategies linked to above, pupils should be able to suggest and justify a systematic sampling technique. At the site consider the length of transect and interval frequency of measurement to ensure reliable and representative sampling.

At each site students can measure some or all of:

Soil pH – using the soil auger or trowel access the soil beneath the plant and organic matter which is generally referred to as horizon A or topsoil. Soil Horizons: Definition, Features, and Diagram. Without touching the soil, as your fingers will have their own pH, collect some soil in a test tube. Either follow the method using indicator solution above or dilute the soil with deionised water and use a simple test strip to identify pH.
Soil depth – using a knitting needle (make sure it has a blunt end) push into the soil as far as possible, make a mark on the needle where it meets the ground and remove, measure in mm how deep the soil is.
Soil compaction – place the tube upright on the ground and drop the knitting needle from the top, allowing it to fall down the tub and pierce the ground. Carefully lift the tube and measure how much the knitting needle has penetrated the ground. Discuss with the students why this might be less subjective / more reliable than the soil depth measurement.
Soil moisture – take a small soil sample (again from the auger or trowel section, this can be taken back to school to test for soil moisture. If you have access to a soil oven (often science departments have this) you can follow the method on this page: Soil – Field Studies Council if not you can simply put the same weight of soil into small microwavable containers and heat in the microwave for 10minute or until a test sample full of the same weight of water is evaporated. Weigh the soils before and after and use the equation below to calculate moisture content:

Presentation techniques

The pupils should be encouraged to suggest suitable graphs for their data, in small groups they might be given pairs of data to present, such as distance down slope and soil moisture or soil depth and soil moisture. These can be presented as bar charts or scattergraphs. Pupils should justify the suitability of their graph choice as well as interpreting the patterns or results.