Applied Geography formerly Rural Training Center, Thailand

pH Test Notes

Introduction

Using strips pHydrion test paper is an easy way to get a general idea of soil acidity (acid) or alkalinity (base). The pH scale goes from 1 (acid) to 14 (alkali) with 7.0 as neutral. It is a coarse measurement and may not be accurate enough to permit comparisons over time. More accurate measurements can be done with pH meters or probes.

Soil pH Notes

Most soil nutrients are more soluble (able to be dissolved) when the soil pH is about 6.5 – 7.0. This is close the good pH range for many soil organisms, such as earthworms and bacteria (6.0-8.0). Knowing the soil pH of your site will help you select plants that will flourish better in your habitat.

Materials / Equipment Needed:
1) A soil sample (about 1 tablespoon will do);
2) pHydrion test paper
3) Distilled water
4) a plastic cup
5) measuring spoons (1 tablespoon) Do not use this spoon for food preparation.
6) wristwatch
7) pencil / pen and notepad

Step 1. Put about 1 tablespoon of soil in a clean container.

Step 2. Add distilled water and stir until the sample is as thick as a milkshake.

Step 3. Let it stand for 1 hour. Check it periodically and add water if needed.

Step 4. Put a piece of test paper in the solution. Leave it in for about 1 minute.

Step 5. Take the test strip out and rinse it with distilled water.

Step 6. Match the color of the test strip to the standard color chart that came with the test paper. Keep a record of your test results.

Water pH Notes

Step 1. Use a clean strip of litmus paper for each test.
Step 2. Dip the end of a strip of pH paper into the water sample.
Step 3. After about two seconds, remove the paper, and immediately compare the color at the wet end of the paper with the color chart provided with that pH indicator.
Step 4. Write down the pH value and color.

Note: the picture of the pHydrion color test chart is shown here. This is a test to see if the colors shown on the webpage are adequate for our recon soil sampling.