Soil pH Testing

Welcome to Educational Checkpoint One – Testing Soil Acidity and Alkalinity!

This is one of three educational checkpoints you will have access to throughout the challenge. Each checkpoint encourages you to explore your soil health a little further, and understand what is happening underground as your undies (hopefully!) decompose.

Soil acidity and alkalinity, otherwise known as soil pH, is an essential measure when looking at our soils. pH testing looks at the power of hydrogen and hydroxide ions in a substance or solution, and can be used in many facets of our day to day life. Here we will just focus on its relevance to soil health. pH is measured on a special scale, called a logarithmic scale, from 0 to 14, with 7 being neutral. The lower the pH (<7), the more acidic something is, the higher the pH (>7), the more alkaline or basic something is. This logarithmic scale means a soil with a pH of 4 has 10 times more acid than a soil with a pH of 5, and 100 times more acid than a soil with a pH of 6.

A well maintained soil pH will ensure the health of a soil is preserved, resulting in happy plants, happy soil biota and happy us! If soil pH is too acidic, or too alkaline, important nutrients are locked away. A low pH in top soil will also reduce microbial activity, which can affect many things, including how our undies degrade! Plant growth and most soil processes, including nutrient availability and microbial activity, are favoured by a soil pH range of 5.5 – 8, but, how do we know what our soil pH is?

In your challenge pack, you will have received a soil pH testing kit, including a vial of Universal pH indicator, a vial of barium sulfate powder, a white card, a pH testing colour chart and a paddlepop stick. Using these resources you will be able to test the pH of the soil where your undies are buried, and make predictions surrounding the overall health of your soil.

We have developed a short video explain how you can do this with your curious young ones, as well as teacher/parent and student activity sheets. Take a look below to discover more.

Download - Parent/Teacher Information Sheet
Download - Student Activity Sheet