Soil Testing

Why take a soil test?

There are a number of reasons that you might consider doing a soil test. Probably one of the most common reasons is to either develop or maintain a good soil fertility program. Soil fertility is one of those things that we just can’t measure accurately via visual observation. So we’d strongly recommend a soil test to help guide soil fertility decisions.

We may also use results form a soil test to guide our plant selection. pH is an important factor to consider when determining what plants your soil can support. Matching the plant to the pH of your soil can be much more cost effective compared to adjusting the pH of your soil to a given plant.

You may also take a soil test to help perform plant diagnostics. Sometimes, nutrient deficiencies and diseases can have very similar symptoms. Performing a soil test can either help us confirm or rule out certain possibilities of what might be impacting our plant’s

health. If you can confirm that there is a nutrient deficiency, then you can work on addressing the health of the plant through nutrient management. If there aren’t any nutrient deficiencies, then you can rule that out and explore other possibilities for why your plant’s health is declining.

When should I do a soil test? How often?

If you have not previously take a soil test, you really could take your soil test any time of the year. However, something to con

sider is when you need to be making nutrient management decisions. For example, it is not ideal to be making adjustments in the middle of a growing season. So, fall or spring may be good times to take a soil test. That way when you get results back, you have plenty of time to make adjustments before you put out plants or crops. Whenever you decide to take a soil test, try and keep it consistent each time. Getting information from similar locations at about the same time of year helps to keep as many factors controlled as possible and allows us to more easily compare results from test to test.

As for how often you should test, the general recommendation is every 2 to 3 years. You are certainly able to do them more frequently, it just depends on your specific goals and your nutrient management plan.

Taking a soil sample

Tools

Having the right tools can help make your sampling process more consistent. Something like a soil probe can be very useful. These provide a simple, consistent way to collect soil cores. If you don’t have a probe, the extension office can loan you one with a $40 deposit (returned or voided upon return of the soil probe), you can also use a shovel or trowel. You can take a few extra steps if you use a trowel to help make your samples more consistent. You can use a tape measure or ruler to measure down the middle of your scoop of soil. You want about 6 inches of soil, but you don’t necessarily need the whole scoop, so you can take the center of the scoop, about an inch in width, to create something similar to a soil core. The excess soil can be discarded. Whatever method or tool you decide to use for sampling, just make sure that it is consistent. Another good tool to have with you is a clean bucket. This will serve as the container in which you place your soil samples.

Sampling Method

What most labs are requesting is something called a composite sample. A composite sample is made up of several subsamples.

The number of subsamples you take depends on the area that is being tested. For example, if you have a small garden or flower bed, you may only need 5-10 subsamples. For larger areas, like your lawn or a larger garden, you might take 10-15 subsamples. If you are working with a multiple acre field, consider somewhere closer to 20-25 subsamples. One test kit can be adequate for up to 20 acres, however, this may vary depending on your specific testing location or goals. Your sampling depth is somewhat crop dependent. We are trying to get a representation of the root zone. For lawns, that can be closer to 3-4 inches. For most other plants and crops, our sampling depth is going to be 6-8 inches.

You should take your samples in a somewhat random pattern. Walking in a zigzag pattern as you take your samples can help you accomplish this random sampling. You might consider doing more than one test if you have multiple soil types, if you have changes in elevation, or if the land undergoes different management practices.

As you collect your subsamples, make sure to remove the very top layer, or the organic matter on top. We really only want the soil horizon where our plants roots will be growing into. An abundance of organic matter or debris from the top layer, or organic layer, of the soil may throw off our results.

With all your subsamples in your bucket, you’ll want to let the soil dry if there is a lot of excess moisture. Once dry, you can mix up the soil and out of your whole composite sample, you’ll only send off about a cup or pint of soil, depending on what lab you go through. Make sure to follow their instructions for sample sizes and collection.

Resources for Lorain County

If you are a Lorain County resident and are interested in doing a soil test, you can reach out to the extension office to ask questions. The office also sells soil test kits for $15. These kits are from Penn Sate and the samples are processed by Penn State’s lab. Results generally seem to take 2-3 weeks to come back depending on the time of year. You can also explore other options as to who you’d like to work with to get your soil sampling done.

Here is a fact sheet with more details and suggestions on doing a soil test: https://ohioline.osu.edu/factsheet/hyg-1132

If you have questions, feel free to call the extension office at 440-326-5851 or email me at becker.643@osu.edu.