Soil Tests

Sunday, February 3, 2019 10:07 AM

I wasn't happy with how my yard looked last year or how my vegetables grew. How much and what kind of fertilizer should I use this year? DJ

This is a question we get quite often. The reality is, that the question, while well intentioned, would be similar me calling you on the phone and asking you how much gas I should put in my car. Your first response would be; well how much gas do you have in your tank now and where are you going? To answer your question, I could look at the fuel gauge and tell you I have half a tank and I just plan on running some errands. In response you could say, well you don't really need gas right now, but you better fill it up at the first of the week

It is the same way with soil. When someone asks how much and what kind of fertilizer they should use, we need to ask some questions. Or in this case, we need to take a soil test which is similar to looking at the gauge to see how much fuel we have.

To perform a soil test you will need something to collect your samples with and a bucket: a trowel or a bulb planter work well. We recommend you get between 15 to 20 samples of soil from locations scattered throughout your yard. Each individual sample does not need to be large but you should dig to a depth of about 6 inches.

Once you have your samples in a bucket, mix them up and remove any sticks or debris. From this mixture of soil, bring a representative sample to the OSU Extension office. We will only need about a sandwich bag sized amount of soil for your test.

When we receive your soil sample, we will send it to the Soil Science Lab at Oklahoma State University for analysis and within 2 weeks you should receive the results. Your results will contain the levels of nitrogen, phosphorus, and potassium found in your soil, along with the pH level. Included will be a recommendation on the nutrients you need to add and how much, along with recommendations on perhaps the nutrients you need to stop adding. Not only is over application detrimental to your growing environment, it is also a waste of money.

The test has a cost of $10, but in all likelihood, it will be the best $10 you have ever spent on your lawn or garden. If you want to test a smaller garden or flower bed, this will require a separate test as those environments would be unique from your lawn. The same instructions would apply. So, grab a bucket and let’s find out what your soil really needs.

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at