Science Buddies: "Ask an Expert"

Hello:

I am doing the science fair project "How does soil affect the pH of water?" with my 6th grade daughter. The reason I am writing to you is because I don't have a full understanding why I am doing this project. The soil if mixed with water might change the pH of water depending on its acidity or basicity. My question is: What am I accomplishing by knowing this? Is it to know if the soil is acidic or basic so it is good for certain plants to grow? Or is there another reason behind doing this project? Please explain it to me so I can explain to my daughter in case she is asked by the judges, the purpose of this project.

Thank you,

Fred

Hi Fred,

Welcome to Science Buddies. I apologize for the delay in responding to your inquiry. I was checking this forum yesterday, but did not see your inquiry at that time.

You are on the right track to help your daughter try to understand the overall significance of her project. I think you are doing this excellent project from the Science Buddies website:

https://www.sciencebuddies.org/science- ... p013.shtml

The importance of this experiment as described is to investigate how the pH of water changes in different types of soil.

The reason this is so important is that the pH of the soil can affect the growth of plants. The background section of this project includes a good description of pH and 3 references that explain the importance of soil pH for plants. Your daughter should be familiar with this information so she can explain the significance of her project to the science fair judges.

https://www.sciencebuddies.org/science- ... background

For example, in the Eastern US where soil pH is frequently low, farmers apply lime to the soil to raise the pH and provide an optimum pH so hay and other crops will grow better. In the Western US, gardeners will notice that plants show signs of iron deficiency and will apply sulfur and other additives that will lower the pH so the iron in the soil become more available to the plants.

Can your daughter think of any practical applications of knowing about soil pH? Perhaps you can go on a neighborhood tour and find plants that need to have the pH of their soil adjusted.

I hope this helps. Please post again in this topic if you have more questions.

Donna Hardy

Hi Donna:

Thank you for your response. However, I am still not 100% convinced with what I am doing.

"The objective of this experiment is to measure how contact with different types of soil changes the pH of water."

I understand measuring the pH of soil will tell us about the soil acidity or basicity. It will tell us which plants prefer that type of soil.

The question is: What does knowing how the soil changes the pH of water have to do will all this?

What effect does the pH of water have on soil? What is the relationship here?

In our experiment, we had to measure the pH of water when mixed with three types of soil over 3 different periods of time: 1 hour, 24 hours, 48 hours, to see if the pH of water changes. Why?

Why do I need to know the pH of water ( if I only need to know the pH of soil, which helps the plants grow better), and what significance this has on the project I am doing.

I think we followed Science Buddies instructions to perform this experiment, but, unfortunately, we came to a dead stop trying to understant why we are testing for the change in pH of water. I thought we only had to know the pH of soil, not necessarily, the pH of water for plants growth.

I apologize if I am bothering you or not being to explain myself any better.

Fred

Hi Fred,

FadiHazar wrote:What effect does the pH of water have on soil? What is the relationship here?

I believe this question will be answered by your daughter's project.

FadiHazar wrote:Why do I need to know the pH of water ( if I only need to know the pH of soil, which helps the plants grow better), and what significance this has on the project I am doing.

Plants need water for photosynthesis and general survival, and they get that water from the soil in which they grow. If the soil changes the pH of the water, then it will affect the pH of the water available to the plant. The plant brings that water into its cells, the pH of the water can affect the pH balance of the cells. So the pH of the water is just as important as the pH of the soil!

I hope that helps. Please post again if you still have questions.

Heather

Donna, thank you for your response.

Fred

Hello Fred:

Heather and Donna have provided wonderful information to you. In addition to their responses, please look over the below website.

http://www.plantea.com/pH.htm

Thanks,
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