This story was originally published in April 2019.
Soil is the foundation of your garden. Knowing what makes up your soil — and how to properly amend it to be the best that it can be — will help make sure your plants thrive this spring. These easy soil tests will help.
Soil tests generally will show the amounts of nitrogen, phosphorus and potassium in your soil, as well as secondary nutrients like calcium, sulfur and magnesium and a number of minor nutrients as well. If you contact your local cooperative extension, you can get a free soil test that will break down the nutrients, composition and acidity of your dirt. Your cooperative extension will also test the soil for potential contaminants such as lead.
But even before you send your soil off to the experts, there are easy soil tests you can do with your own hands to just get an idea of what you are working with. Here are a few soil tests you can do today to help identify any major problem areas in your garden.
The squeeze test
This simple soil classification test brings a whole new meaning to getting your hands dirty. Soils are generally classified as clay soils, sandy soils or loamy soils, and you can quickly assess what category your soil falls into with this simple test.
Take a handful of moist, not wet, soil from your garden. Squeeze it tightly, and then open your hand.
If it holds its shape but crumbles with a gentle poke, you likely have loamy soil, which is ideal for retaining moisture and nutrients.
If it continues to hold its shape even after you poke it with your finger, your soil is probably made of nutrient-rich but slow-draining clay. You can help break up the soil with mulches and drainage aids such as perlite and vermiculite.
If the soil falls apart as soon as you open your hand, it is sandy, which has trouble holding in nutrients and moisture but drains easily. You will probably need to add a nutrient-rich compost and mulch to help your plot retain moisture.
The puddle test
Another important aspect of your soil is drainage, which allows water to pass through quickly without pooling. If your soil has poor drainage, the roots of your plant can rot. Culinary herbs are especially susceptible to root rot from improperly drained soil.
To test your soil drainage, dig a hole about six inches wide and one foot deep. Fill the hole with water, let it soak in completely and then refill it with water. Keep track of how long it takes for the second pool of water to drain. If it takes more than a few hours, you likely have a drainage issue with your soil the water takes more than four hours to drain, you have poor drainage, which can be amended with proper compost and mulch along with drainage aids like perlite, vermiculite or even sand.
The worm test
Healthy soil is biologically active. An abundance of worms is a surefire sign of a healthy environment with all the right microbes and bacteria for plants to thrive.
Dig a hole one foot across and one foot deep and place the dug up soil on a tarp or sheet of cardboard. Sift through the soil with your hands as you place it back into the hole, counting the worms as you go.
If you find at least 10 worms, consider yourself lucky and your soil healthy. Any less, and there may not be enough organic matter in your soil, or perhaps your soil might be too acidic or alkaline. You will need an official soil test to pinpoint the problem and figure out how to solve it.
The wire test
Soil that’s too compact will inhibit root growth, choke off available water and prevent worms and other vital soil critters from moving freely.
To test your soil compaction, plunge a wire flag vertically into the soil. Mark the depth at which the wire bends, where it can no longer be pushed down straight. Ideally, you will be able to easily push the wire down a foot or more. The sooner it bends, the more compacted the soil. To help ease compaction, you can amend the soil with organic material and aerating inorganic materials and avoid walking on plots when the soil is wet.
The vinegar and baking soda test
The acidity or alkalinity of your soil, or pH, is important. Some plants thrive better in more basic or more acidic soil, but soil that’s too extreme at either end will prevent your plants from getting nutrients. It can even poison them.
One easy way to determine the pH of your soil is to test it with vinegar and baking soda. Collect a cup of soil from different parts of your garden and divide it into two separate containers. Add half a cup of vinegar to one container with the soil. If it fizzes, you likely have alkaline soil with a higher pH, which may need a fertilizer that is higher in sulfur and acidifying nitrogen. Some plants tolerate alkaline soil, and others such as parsnips and peanuts will thrive in the “sweet” soil.
If your soil does not fizz after doing the vinegar test, then add distilled water to the other container the soil is a little muddy. Then, add half a cup of baking soda. If it fizzes, you have likely have acidic soil with a lower pH. Some acid-loving plants such as blueberries and cranberries prefer this kind of soil. Otherwise, pulverized limestone will help neutralize the soil.
If your soil does not react at all, then you may be lucky enough to have neutral with a pH of 7. Most plants thrive with this soil composition, but check with your local cooperative extension to be sure you are using the best plants for the pH of your plot.
The cabbage test
If you are looking to get a more accurate reading of where your soil stands on the spectrum of acid to alkaline, you can either purchase a home testing kit or use this slightly more advanced DIY test using red cabbage.
Red cabbage contains a pigment called flavin, which not only dissolves in water, but also will turn red in acidic solutions and greenish-yellow in basic solutions (neutral solutions will result in a purplish color).
Let one tablespoon of soil from your garden dry on a white saucer or plate. Meanwhile, bring one cup of distilled water to a boil in a pot with a lid. Add two cups of chopped red cabbage into the boiling water, cover and boil until the water turns dark purple.
Pour the mixture through a colander to remove the chunks of cabbage. Let the solution cool.
Use the dropper to add enough cabbage water to thoroughly wet the soil. Allow to sit for a minute, then tip the saucer so the water runs to the side. If it is blue or green, the soil is alkaline. If it is red, the soil is acidic. If the color of the water drained from the soil is purple or purple-blue, it means the soil pH is neutral, which is ideal for most plants.
When it comes to figuring out exactly what your soil needs to thrive, these tests are not a substitute for a complete report from your cooperative extension, but they will help you get an idea of what you are working with and become better connected to the foundation of your garden.
