Archive for Thursday, September 20, 2007

Submit soil for a test with these simple steps

September 20, 2007

<strong>Editor's note:</strong> Jennifer Smith, new Douglas County Extension agent in horticulture, will begin writing the Garden Calendar after a hiatus filled by Stan Ring, who remains horticulture assistant with the Extension office.


When I became the new County Extension agent in horticulture, I didn't know what I was getting into. Don't get me wrong. Extension is a service I have been aware of since I was a child, but I never realized the depth of the organization. This is a resource that truly has something for everyone.

One of the things I do is analyze soil test results and write recommendations. If my old soils professor were here, he would be worried. Not to say soils class wasn't my strongest subject, but I was interested in more important things than the four-letter D-word (dirt).

Interestingly enough, I didn't want to spend much time studying the soil, because I was concentrating on growing plants. Making the connection between the two took me longer than it should have. I fertilized my plants, and picked out my fertilizer by what the bag said - "good for houseplants" or "good for roses." The real question should have been "What does my soil need?"

You may already know that you can have your soil tested. For a small fee (usually $10 per sample), the Kansas State University Soil Testing Lab will determine the pH and amount of phosphorus and potassium in your soil. I will use that information to write recommendations on how to adjust your pH and what kind of fertilizer to use for optimum plant health. The lab offers optional tests for an additional fee, including nitrogen, organic matter, minor elements and soluble salts tests.

For lawn soil testing, pick an area to be tested (front yard, backyard, etc.). To attain a good representative sample, take samples from 10 or more random places within that area. You can use a knife, trowel or spade to cut slices of soil 3-4 inches deep. Place all of the soil in a clean container, removing rocks and plant material, including thatch (grass roots and stems that compress just above the soil surface). Mix the soil and take approximately 2 cups of soil out and place in a separate container to be tested. A small plastic bag or other sealable container would be appropriate.

For garden soil testing, pick an area as above. You may want to section off the vegetable garden for samples, depending on what crops have been grown there. Again, take samples from 10 or more random places within each area, but this time go 6-8 inches deep. Clean, mix and prepare the sample as above.

For both lawn and garden tests, avoid taking samples from areas which are different unless you want a sample of just that site. Typical places to avoid are backfill ditches, burn piles and around plants that have been fertilized recently. If the soil is extremely wet, spread it out on newspapers to dry before mixing and bagging. If you have multiple samples, make sure to label each appropriately.

Bring samples in to the Douglas County Extension Office at the Douglas County 4-H Fairgrounds, 2110 Harper St.

You could be wasting your money applying fertilizer that your lawn or garden doesn't need. Many samples that are tested have more than adequate levels of phosphorus and potassium. Overfertilizing can cause excessive vegetative growth (less flowers and fruit), or turf that doesn't withstand heat and drought stress.

For more information, visit

- Jennifer Smith is the Douglas County Extension agenthorticulture for K-State Research & Extension. She can be reached at 843-7058 or


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