Soil pH can be measured by a number of kits and test strips available online, or you can measure your soil directly by using some common ingredients found around your home, along with a bit of creativity.
If you think back to your high school chemistry class, the words “pH scale” probably ring a bell. As you may remember, the pH scale is a very important metric that affects everything around us, from the healthy mineral balance of our blood to the water we drink every day and the soil where we grow our crops. While we may be familiar with the term pH, let’s take a more in-depth look at the effects and important of pH, particularly in terms of soil quality!
What is Soil pH?
The pH scale is a universally accepted scientific approach for measuring the acidity or alkalinity of a substance. Soils vary in their alkalinity or acidity depending on a number of factors, including climate, mineral content, and the concentration of organic matter in the soil.
The pH scale ranges from 0 to 14. The lower end of the scale means the substance is highly acidic, the upper end of the scale signifies high alkalinity, and a measurement right in the middle (7) means the substance, in this case soil, is neutral. For example, a pH of 0 has the same acidity as battery acid. 7 is a neutral substance such as distilled water, and 14 is high in alkaline content, like the substance lye, which is a key ingredient in homemade soaps.
Why Does Soil pH Matter?
Soil pH is a complicated and fascinating science that offers a way to measure how available essential nutrients are to the plants and crops growing in a given sample of soil. The pH scale of your soil is critical to ensure the viability and health of what you plan to grow! Most vegetables and plants cannot survive in soils that are very high in acidity or alkalinity. It’s important to test your soil before you begin planting so you know what crops are likely to do well, and which will not survive. This is also a key indicator of what appropriate measures you should take to balance your soil.
You ideally want your soil to have a pH close to neutral (7) or just a little on the acidic side (6.5 on the scale). However, fertile soils can range from 3 to 10 pH, and some plants can thrive in more acidic or alkaline conditions, which is why it’s helpful to know your soil pH before you start buying seeds. If your soil is high in acidity or alkalinity, there are a few things you can do to bring the soil close to neutral again, which we’ll cover below.
It is important to test your soil to ensure it is viable for the plants you plan to grow. So, how do we test soil?
How to Test Soil pH at Home
While there are many soil pH testing kits you can order online, you can also do a few surprisingly affordable and easy tests at home to determine the pH level of your soil.
There are two main methods you can use to test soil pH from home. The first we’ll cover is quite quick and easy.
Materials you’ll need:
- Two bowls or containers
- ½ cup white vinegar
- ½ cup distilled water
- ½ cup baking soda
- 1 cup of soil from your garden
- Evenly divide the soil into the two bowls.
- In one bowl, pour ½ cup of white vinegar over the soil. If it fizzes, you have alkaline soil and the test is complete! Your soil likely has a pH of 7-8.
- If, however, the white vinegar didn’t create a reaction, pour ½ cup of distilled water into the other bowl of soil. Distilled water is important here to ensure neutral pH levels. Don’t use tap water, as it usually contains minerals that alter the pH level of your sample.
- Mix soil and distilled water until the water is well incorporated.
- Add ½ cup of baking soda. If your soil bubbles or fizzes, it is acidic, and likely has a pH of 5-6 on the scale.
If no reaction has occurred in either of the samples, you have neutral soil, which is ideal for most plants, and you won’t need to alter the pH level at all!
The second at-home test takes a bit longer, but is equally effective. This is also a great activity to do with kids.
Materials you’ll need:
- ⅓ head Red cabbage (red is very important, as other cabbage won’t work)
- Quart of distilled water
- Four glasses or jars (make sure you can see through them!)
- White vinegar
- Baking soda
- ½ cup of soil
- Pan for boiling
- Shred ⅓ head of red cabbage.
- Combine cabbage and quart of distilled water.
- Bring to a boil and let simmer for five minutes.
- Strain out the cabbage and pour even amounts of the purple cabbage water into the four jars.
- Allow to cool.
- Add a little bit of white vinegar to one of the jars. You will see it turn a bright pink color
- In another jar, add the baking soda. The purple water will turn blue.
- You now have three pH level samples to compare your soil to: pink is acidic, purple is neutral, and blue is alkaline
- Next, add your soil to one of the two jars of purple water, leaving one as your sample.
- Wait a few minutes and see what color the water with your soil in it has turned. If it’s still purple after a few minutes, you have neutral soil. If it is closer to blue in color, it is high in alkaline content, and if it’s pink, it is acidic!
If you’ve found that your soil is too high in acidity or alkalinity, don’t despair! You can add substances to your soil to bring the pH level to a neutral level. If your soil is too acidic for your purposes, you can add wood ash or lime. If it’s too alkaline, add sulfur or pine needles to the soil.
If you have soil that is higher in acidity (5-6 on the pH scale) and don’t want to amend the soil by adding organic matter, consider planting the following vegetables:
- Bok choy
- Lettuce and other leafy greens
On the other hand, if your soil has a lot of alkalinity (8-9 on the scale), consider these plants:
- Brussels sprouts
- Cabbage and Chinese cabbage
- Grape vines
- Lima beans
- Mustard and other leafy greens
- Peach tree
- Swiss chard
- Methods of soil analysis: part 3 chemical methods
- Soil Science Society of America Journal
- Methods for assessing soil quality
- Chemical and microbiological properties