Soil pH

Introduction

Gardeners sometimes find that their plants do not grow very well. This is often because the pH of the soil is not suitable for a particular plant. For example, the beautiful rhododendron shown in the picture will only grow in
acidic soil. 

In this activity you will be using your research skills to find out about:

  • soil pH
  • soil-testing kits
  • how to change soil pH. 

You will be using your literacy skills to prepare a leaflet for gardeners explaining why they might need to test their soil pH and giving them instructions on using a soil-testing kit. 

Task

You are going to make a leaflet for gardeners explaining why they should test the pH of their soil.

Your leaflet should :

  • explain what pH is and what the values mean
  • explain why gardeners should test their soil pH
  • explain how to test soil pH
  • advise gardeners what to do if the pH of their soil is too high or too low
  • fit on one folded sheet of A4 paper
  • use language that can be understood by the general public and people who do not have a good understanding of science. 
Process

Step 1

Find out what happens to plants if the soil pH is too high or too low.
Find some examples. Use this information to persuade gardeners that it really is worth testing the soil. 

Step 2 

Find out what is contained in a soil-testing kit and how it should be used. In your leaflet you will need to give gardeners instructions on using a soil-testing kit and advise them what to do if the pH is wrong.

Step 3 (extension)

Find some information about why soil pH affects different plants in different ways.
Refer to the nutrients that plants need. 

Step 4 

Plan your leaflet. 

Step 5

Now make your leaflet. Make sure that it is useful for gardeners who do not understand about the importance of soil pH. 

Sources

Why and how to test soil pH

Website for gardeners to help them grow plants more successfully.

http://www.greenfingers.com/articledisplay.asp?id=489 http://www.enjoy-your-garden.com/soil-ph-test-kit.html

 

Changing the pH

Website describing what to do if the soil pH is wrong.

http://www.sunset.com/garden/garden-basics/acid-alkaline-soil-modifying-ph-00400000015165/

 

Soil, pH, and plants (extension)

This website has lots of detail about the effect of pH and how to change it. It gives tables showing the best pH for many plants. 

http://web.bethere.co.uk/fm/soil/ph/p01.htm

Evaluation

You have made a leaflet for gardeners explaining why they might need to test their soil pH and giving them instructions on using a soil-testing kit.  

Look at the questions below and think about whether you have met the brief. 

  • Have you included a clear, accurate scientific explanation of pH?
  • Have you given convincing reasons why gardeners should test the pH of their soil?
  • Have you given some examples of plants that will not grow well at particular
    pH values?
  • Are your instructions for using a soil-testing kit clear and helpful?
  • Have you explained what gardeners can do if their soil pH is wrong for the type of plants they are growing?
  • Have you given a summary saying how much better the plants will be if grown at the right pH?
  • Does your leaflet fit on one folded sheet of A4 paper?