Understanding Soil pH Level to Grow Healthy Plants

Beautiful, Healthy Plants

Soil pH Level's Affect on Plants

In some ways, plants are like people. To grow into strong, healthy plants, they need five basic requirements for life. These requirements are air, sunlight, water, food, and the right type of environment. For a plant, the pH level is more important than people think. Not only do different plants like different soil pH levels, pH affects other factors too. Soil pH can affect nutrient availiability. For most plants, the soil needs to have a pH between 6.0 and 6.5 for nutrients to be available.

pH Scale

Reprinted from staff.jccc.net/PDECELL/chemistry/phscale.html
Reprinted from staff.jccc.net/PDECELL/chemistry/phscale.html


Reprinted from http://www.eskom.co.za/nuclear_energy/fuel/atom.jpg
Reprinted from http://www.eskom.co.za/nuclear_energy/fuel/atom.jpg

The pH scale

To understand soil pH, a basic understanding of chemistry is important. Everything in the world around us is made up of subatomic particles. An atom consists of three subatomic particles: protons, neutrons, and electrons.

A neutral atom has an equal number of protons and electrons. The protons and neutrons live in the nucleus or center of an atom while electrons fly around the nucleus. While protons have a positive charge, electrons have a negative charge.

In its pure state, water is neutral. Composed of H2O, it has two hydrogens and one oxygen. However, when other compounds are dissolved into water, the bonds of water tend to break apart. While the hydrogen ions are negative, the hdyroxyl ions are positive.

The pH scale is a logarithmic scale that measures the hdrogen and hydroxyl concentrations in an aqueous solution. It ranges from 0 to 14. Seven is neutral. Neutual means the concentration of hydrogen ions is exactly equal to hydroxide ions. While anything above seven is basic (alkaline), anything below seven is acidic. For each pH level above or below seven the pH levels increase tenfold.

Plant Nutrients

Reprinted from http://www.umext.maine.edu/piscataquis/gardening/2004/vol2iss1/nutrie2.gif
Reprinted from http://www.umext.maine.edu/piscataquis/gardening/2004/vol2iss1/nutrie2.gif

pH and the Availability of Nutrients

Soil pH Level and Plant Nutrition

Plants get most of their nutrients from the soil. In fact, there are seventeen essential nutrients, and fourteen of them come from the soil. However, before a plant can utilize a mineral, it must be able to dissolve into the soil solution. Most minerals are dissolvable in neutral or slightly acidic soil. If the soil is too acidic, when minerals dissolve, it can increase the concentration of metal ions to toxic levels. On the other hand, if the soil is too alkaline, mineral deficiencies may occur because the minerals are unable to dissolve. In addition to mineral solubility, soil pH levels also affect the microrganisms that live in the soil that break down organic material. To avoid problems with most plants, the soil pH level should be between 5.5 and 7.5.

How is Soil pH Measured?

Soil pH can be measured with either a pH meter or indicator dyes. Most gardeners use indicator dyes rather than meters because the indicator dyes are less expensive. However, if you plan on taking a lot of pH tests, in the long run, it might be less expensive to buy a pH meter. When you're using indicator dyes, the soil sample is saturated with dye. The color of the sample will indicate the pH. Since the dyes are not as accurate as the meters, you might want to take several samples.

If your plants are struggling, you might want to consider testing the pH of your soil. You may think to yourself, pH doesn't matter. However, that is not true. Sometimes, even when you fertilize your plants, if the pH level is not at the right level, the fertilizer won't be available to plants.

Soil pH in the United States

Reprinted from http://www.fossweb.com/CA/modules3-6/Environments/activities/delgap/images_sized/phfield2001.GIF
Reprinted from http://www.fossweb.com/CA/modules3-6/Environments/activities/delgap/images_sized/phfield2001.GIF

Do Soil pH KIts Work?

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Comments 12 comments

jayjay40 profile image

jayjay40 7 years ago from Bristol England

Thanks for the information, i know understand more about soil testing-thanks

seamist profile image

seamist 7 years ago from Northern Minnesota Author

You're welcome. I am glad it helped.

Chris 6 years ago

Great resource. I think understanding your soil's profile is crucial to success in the garden. Armed with that info you are better able to make decisions and only make change s as needed, rather than adding components just because someone recommended it. Thanks for posting this information.

seamist profile image

seamist 6 years ago from Northern Minnesota Author

You're welcome, Chris. Thank you for leaving a comment.

Billy 6 years ago

Wow thanks a lot for this very interesting post

I am reading this because my friend is watering his plants with water from his pond which has a pH of 10.4 !!

will these plants grow well like this ?

seamist profile image

seamist 6 years ago from Northern Minnesota Author

Hi Billy

Although I have a science degree, there are too many factors to be able to answer this question. Although most plants like a slightly acid soil, different plants have different needs. For example, blueberries like an acidic soil. Secondly, the existing pH of the soil would also affect how the pH of the water would affect the plants. If the soil was very acidic, watering with an alkaline water might help neutralize it. The only advice I can give you is watch your neighbor's plants and see how they do. Good luck and thanks for commenting!

kgnature profile image

kgnature 6 years ago from North Carolina

You've done a great job with a touch topic. Thanks!

seamist profile image

seamist 6 years ago from Northern Minnesota Author

Hi kgnature

Thank you.

sara 6 years ago

Hello! I was reading this because I am doing a research paper for my science fair project and I am seeing what type of water will have the best effect on plants. I decided to use your information and since I have to do InText Citations, I was wondering the year this was written...That would help a lot! Thank you so much for all the useful information!

seamist profile image

seamist 6 years ago from Northern Minnesota Author

Hi Sara

I'm glad you found the article helpful. It was published on 12-25-09. Good luck!

Connor  5 years ago

Im currently Sitting in one of my science classrooms :) I am doing my GCSE course work and I had to find out about pH levels thank you for the information, it was very helpful. :D



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