The only way to know if your soil needs compost or fertilizer is to test the soil. Learn the correct way to get a representative sample of your garden or flower bed to send to your local county extension office. You'll be able to find out how your soil tests for pH, phosphorus, potassium, nitrogen, and organic matter.

Produced by the Department of Communications at Kansas State University. For more information, visit our website at:

How to Test Your Soil for Nutrients

Take a shovel, it can be four inches, six inches, or eight inches, and get what we call a shovel slice. For an accurate sample, start by digging a hole, very carefully. It should have a flat side on the hole, so that you can get a nice flat sample. And then, sample about an inch depth, meaning an inch thick.

Once the sample is on your shovel, break away the soil until you have a rectangle. What this does is give you the same amount of soil from the bottom of the hole, and the top of the hole, so you get a more accurate reading. Sometimes there’s a gradation, and there are more nutrients at the top or at the bottom. Then find a container or a bucket, and put it in the container. In a plot this size, I would do that about ten times.

When I have my 10 subsamples, I would take that same shovel, break up any clumps, and stir the soil. Let’s pretend I have my 10 subsamples. Then you’ll need just one shovelful as your final sample to send in to the lab.

You can send in a fresh sample, but it’s better to let it air dry before you send it. To do that, take your subsample (the one cup of soil you’ve taken from your subsamples), and put it out on a newspaper for about two days. Then take that to your county office, and have them send it to K-State.

You can put the sample in a plastic bag, or a paper sack. Your county office may also have containers, and you can ask K-State to run tests on pH, phosphorus, potassium, nitrogen, and organic matter. Each of those will tell you a different, but very important thing about your soil.

This feature story prepared with Rhonda Janke, Kansas State University Research and Extension, Sustainable Cropping Systems. For more information, visit your local county extension office or visit our website at

Horticulture Newsletter

KSU Horticulture Newsletter

Get more information from our weekly newsletter.

Find Your Local Office

Have questions or need help?

Local Extension Office Map

Click the map to find your Local Extension Office.

YouTube Videos

YouTube Videos

Watch K-State Research and Extension Videos.

Kansas Healthy Yards Tagline