I talk a lot about soil testing. I feel that it is one of the most important chores that you do that will help have a healthy lawn or garden. Without knowing what minerals and nutrients are in the soil, how do you know if your plants will be able to grow and thrive? As long as the ground is not frozen, now can be a good time to get your soil tested. That way, you can know what needs to be added in the spring and be prepared ahead of time. Here are a few quick thoughts from Ward Upham, K-State Research and Extension’s horticulture expert about soil testing I thought I would share this week.
Most gardeners think that soil tests are done only to find out what nutrients are deficient. However, it is just as important to know if you have adequate levels of nutrients so you don’t add unneeded fertilizer. The most basic soil test checks pH and the levels of phosphorus and potassium. Most of the lawn and garden soil tests that come out of our soil-testing lab show more than adequate levels of both phosphorus and potassium. If those nutrients are not needed, applying them is a waste of money and can be a source of pollution. In extreme cases, excess phosphorus can interfere with the uptake of micronutrients. So, if you haven’t taken a soil test in several years, take one this spring.
Begin by taking a representative sample from a number of locations in the garden or lawn that goes from the surface to 6 to 8 inches deep. Mix the samples together in a clean container and select about 1 pint of soil. For more detail on taking a soil test, see  http://www.agronomy.ksu.edu/soiltesting/p.aspx?tabid=40. Take the soil to your local K-State Research and Extension office to have tests done at the K-State soil-testing laboratory for a small fee. A soil test determines fertility problems, not other conditions that may exist such as poor drainage, poor soil structure, soil borne diseases or insects, chemical contaminants or damage, or shade with root competition from other plants. All of these conditions may reduce plant performance but cannot be evaluated by a soil test.
The next piece I wanted to share with you is about taking soil samples when it is wet. With the amount of precipitation we have had this winter, your soils may be wet and therefore difficult to get a sample. Here are a few items that may help you get an accurate sample even when the soil is less than ideal.
In many parts of the state, wet soils may be a good problem to have. So let’s say you just had a rain and need to take a soil test. It would be best to wait until the soil dries but it is possible to take soil tests when soils are wet though there are precautions. Soil samples should be air-dried before being submitted for testing. Do NOT use artificial means of drying such as an oven or microwave as such treatment may result in inaccurate readings of nutrient levels. Also, be sure to use a clean container to collect the sample. Wet samples are more likely to absorb foreign materials adhering to the container, which may also influence soil test results.
For information on how to take a soil sample, see
http://www.agronomy.k-state.edu/services/soiltesting/home-owner-samples/soil-analysis/samplecollection.html