Soil Acidity and Testing

So, I’ve been covering the acid-base chapter in my chemistry classes at work this week, and it (and family) made me think I should really write a post on soil acidity, what it means, and how to test for it, as well as mention some plants (or at least link some) that prefer the different types of soils.

Now hopefully everybody realizes that pH is a measure of how acidic or basic something is and ranges from 0-14.  0-7 is acidic, 7 is neutral, and 7-14 is basic or alkaline.  If you didn’t know, now you do!.  On Earth, the majority of our soil is either acidic or alkaline , very little of it is actually neutral in pH.  This can be important, because it can determine what will grow well where, and gardeners need to be aware of ways to remedy this if they don’t like their soil type.

Soil testing is something you should do before you dig up the yard for your garden (guess I still have time since the tiller hasn’t been dropped off).  You can either go out and buy a soil testing kit at your local hardware store (the big chains have them too), or try a couple of these home solutions.

1.  Vinegar & Baking Soda Test.
Put a handful of soil into a container, and add ½ cup of vinegar.  If the soil bubbles or fizzes, it is alkaline.  If no reaction occurs, put a handful of soil into a container, add ½ cup of pure water, mix well, then add ½ cup of baking soda.  If it bubbles or fizzes, then your soil is acidic.

2.  Litmus paper can be bought at Sears and a few other stores.  You should need one or two strips, and the pH color code is usually on the package.  Add ½ cup water to your soil, mix well, and touch the litmus paper to the solution.  Use the code to figure out if your pH is less than or greater than 7.  Excess litmus paper can be used to determine the pH of your household cleaners (you’ll be surprised) or given to the kids to use to test random solutions.

Remedying Acidic Soil:
Mix in some wood ash or lime.  Make sure you take your time, since small changes are best and give the changes time to take hold.

Remedying Alkaline Soil:
Mix in some pine needles or some sulfur.  Again, small changes are best.

For a list of plants that prefer acidic soils, check out

and for ones that prefer alkaline soils, look at

Bachman’s has good lists for both as well as recommends what plants you can use to tell you if the soil might be acidic or alkaline.


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