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What Happens at a Soil-Testing Laboratory?

Here's what happens to your soil sample in the lab

Antonio Reis, edited by Cari Delahanty

You might have heard of gardeners getting their soil tested, and that this can be a great way to learn more about the soil and what nutrients it might be missing. But how exactly do you get a good soil test? And once you ship your soil off, what really happens at the soil-testing lab?

In this video, executive editor Danielle Sherry teaches you how to take a soil sample and then brings you behind the scenes at the University of Connecticut’s soil-testing laboratory.

How to take a soil sample

Step 1: Using a spade or a trowel, take thin slices of soil from 10 or more random yet evenly distributed spots in your sample area. The holes you dig should be about 6 to 8 inches deep.

Step 2: Put each of the slices of soil in a clean container, and then thoroughly mix them together.

Step 3: Transfer at least one cup of the soil into a plastic bag and seal.

Step 4: Place the plastic bag in a mailing envelope or small box, and send it off to your testing facility. Most testing facilities provide a questionnaire for you to fill out and send along with the sample.

How a technician will test the soil

Step 1: Extract the nutrients. A solution is added to the soil that extracts the nutrients in a soluble form.

Step 2: Measure soil PH. Ionized water is added to a small cup of the soil and then stirred, rested, and stirred again. The soil PH is then read on a PH meter.

Step 3: Measure phosphate levels. Using the solution with your soil’s nutrients, a piece of analytical equipment determines the amount of phosphorus in your soil.

Step 4: Measure the rest of the elements. Another machine is used to measure the other elements in the soil solution.

All of this information is compiled into one report and sent back to you. This report will tell you your soil’s PH as well as the nutrients in your soil and whether they are at a below-optimum, optimum, or above-optimum level.

From there, the power is in your hands! Add compost if that’s appropriate, and do some research on your plants to find out what they might need to be as healthy as possible.

Previous: Soil-Testing Basics: The ABCs of NPK Next: How Is Your Soil Texture?
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