Testing Soil

There are many methods for testing soil, including just measuring PH, or more detailed tests to pinpoint problems. (kram-9/Shutterstock)

Soil is your plants’ food. And, just like you, your plants need nutrient-rich food to stay healthy. But too much or too little nourishment can have a negative effect, so it’s important to understand the condition of the soil you are working with and what your plants need. For optimum results, experienced gardeners recommend testing the soil.

What Does a Soil Test Measure?

A new gardener has some options on where and how to start growing. If you have a yard, you can find a patch of land and till the soil, or you can purchase soil from your local garden center and build raised beds. Either way, you should measure the current health of your soil before you begin planting or fertilizing. But what exactly should you be looking for when you test?

Soil tests measure pH level and detect deficiencies in nutrients such as phosphorous, iron, nitrogen, and potassium. Experienced gardeners have found that most plants, including vegetables and flowers, are happier when the soil is slightly acidic (6.0 to 6.5). Some plants, like blue hydrangeas and cranberries, require an even higher level of acidity (a lower pH number). The results of your soil test will reveal the current level.

Once you have this information, you can enhance any deficiencies with fertilizer to get your soil to the desired state; not all soils need fertilizer. If there is too much acidity, you can add a neutralizer such as pulverized limestone or bentonite clay.

Soil Testing Methods

Testing your soil doesn’t have to be done by a professional as there are at-home methods you can try. Alternatively, you can send samples to a professional lab or to your local cooperative extension or university for more detailed results.

A soil test kit is the best way to measure nitrogen, phosphorous, potassium, and pH with fast results. Most kits come with color-coded containers to separate the different measurements, as well as capsules that induce a chemical reaction. It is recommended that you take samples from different areas of your yard or raised bed. Also, remove any leaves, grass, or other debris from the surface and dig about two inches below the soil to get the best sample, as the representative quality of your soil sample is going to make a difference in the accuracy of your soil test.

Other methods can test your soil’s pH, but they may not be able to pinpoint any problems. For example, using litmus paper with a color chart is a simple chemistry test for acidity or alkalinity level. Place a strip of the litmus paper in a mixture of equal parts soil and distilled water. Mix well and let it sit for about 10 minutes before inserting the paper in the soil and water combination. Wait for the color to change, then match it with the color chart. It is recommended to take three representative samples to get a good range. Although you can get a reliable acidity reading, this method does not test for individual nutrients.

How Often Should I Test ?

You should test your soil anytime you plan to start a new garden, at least a month before your seedlings are planted. During the growing season, it’s a good idea to conduct testing if you notice problems in your plants’ growth. Afterwards, you can conduct routine tests every three years, and if your soil consistently tests well, you can extend it to five years.