Complete Guide to Soil pH Testing

Soil pH is very important for optimum plant growth.  The term pH is a measure of how acidic or alkaline a substance is, in this case, the soil.  It ranges from 1.0-14.0, with 7.0 being called neutral.

The lower the number the higher the acidity.  The higher the number the more alkaline, or less acidic, the soil is.

The acidity or alkalinity of the soil influences how easily plants take up nutrients.  Too much acidity and the nutrients in the soil dissolve slowly or not at all.  The ideal pH of soil is 6.5-7.0.

Fertilizing the soil is of little use because it cannot be utilized by the plant.  High alkaline soils can indicate high levels of sodium that can negatively affect plant growth.

Soil pH testing can be easily accomplished.  The items needed for this task are commonly found in almost everyone’s home.

Materials needed:

garden spade or shovel
bucket to mix soil
2 containers
measuring cup
tablespoon
white vinegar
distilled water
baking soda
pH test strips, also known as litmus paper, optional

Step 1: Collecting Soil Samples

A flat spade works great for collecting your soil samples.  To obtain a good sample, dig down at least 6-8 inches and make a hole.

Position the spade 2 inches back from the opening and go down the depth of the hole.  Take about a ½ cup soil from the length of the spade.  This is the soil that you will use for your sample.

Put the sample into the bucket you will be using.  Do this in several different areas of your garden and then mix the samples together well.

Scooping soil from only the top layer will not give you an accurate result.  You need to get soil from where the roots of your plants will be taking in nutrients.  If you prefer, each location can be tested separately.

Step 3:  Testing the Soil

Put two tablespoons of soil into separate containers.

Add ½ cup vinegar to one of the containers.

If the mixture fizzes this means that you have alkaline soil with a pH higher than 7.0.

If the mixture does not fizz, then add distilled water into the 2nd container of soil until it is muddy.

Sprinkle baking soda on the mud and watch for a fizz reaction.

A fizzing reaction means you have acidic soil with a pH below 7.  If there is no reaction then you have soil that is neutral, the preferred range for most plants.

To get an actual pH measurement of the soil you can get pH test strips, also known as litmus paper, with the full range of readings, 1.0-14.0.   Mix some of your soil with distilled water until it is the consistency of a milkshake.

Put a strip in the mixture for about 20-30 seconds, then dip in distilled water to clean off the mud.  Now compare the color of the strip with the color codes furnished with the test strips.

Bonus Information

You can amend the pH of your acidic soil by adding ground agricultural limestone in the fall. It takes about 6 months for the lime to change the pH of the soil.  The limestone can replace calcium and magnesium that rain has leached out of your soil.  To correct high alkaline soil apply well-decomposed organic matter, such as compost.  You may also add gypsum or powdered sulfur to your soil to bring down the alkalinity.