D. Crowley, 2009

To know how to measure environmental factors

Wednesday, April 19, 2023

How could you sample a snail – tracking its movements / finding out how many there are?

Tagging would easily allow you to spot the snail, but how could this affect it?

Tagging could make the snail far more obvious to predators…

Soil contains a variety of things, including: weathered rock particles; decaying dead plants and animals (humus); water; air; living creatures

Soil supplies plants with water and nutrients to help them grow (as well as helping them anchor to the ground

Soils can vary greatly – how much weathered rock they contain; how much humus they contain; how much water is stored etc…

Soil pH is also different (as soils contain different rocks which have different chemical compositions) – pH of soil affects the availability of nutrients which means different plants grow better in different soils…

Your task is to test the pH of different soils – record the pH of each soil sample (using the pH indicator): -

Now repeat you experiment, but this time use the data-logger instead of the universal indicator solution

How does the accuracy and precision differ?

Accuracy – is your measurement close to the true value? Precision – what scale of measurement has been taken?

Plants which grow best in acidic soil include . . . Daffodil (6 - 6.5) Holly (5 - 6.5) Blue Hydrangea (4 - 5) Rhododendron (4.5 - 6)

Plants which grow best in neutral soil include . . . Bluebells (6 - 7.5) Foxglove (6 - 7.5) Pink Hydrangea (6 - 7)

Plants which grow best in alkaline soil include . . . White Hydrangea (6.5 – 8)

Most plants grow best in slightly acidic soil – why do you think this is a good thing for gardeners?

Rain is slightly acidic – naturally decreasing the pH of the soil for the gardeners!

What could we do if our soil was too acidic?

Lime (calcium oxide) is a base, and can be added to soil, neutralising the acid and increasing the pH

What could we do if our soil was too alkaline?

The easiest way to decrease the pH is to sprinkle natural rain water on the land (as this is slightly acidic) neutralising the alkaline so lowering the pH

Complete the hydrangeas worksheet

1. More than pH 5 because his hydrangeas produce pink or white flowers

2. Less than pH 5 because her hydrangeas produce blue flowers

3. Adding acid to the soil turns the hydrangeas blue! Natural rain would work well (lowering the pH)

4. Adding alkali to the soil turns the hydrangeas pink! Lime would work well (increasing the pH)