No Cooperative Extension Service Educator/Agent worth his or her salt can ever present an educational program without recommending that you take a soil test. Some people think this is just because the agency makes a profit on each one they sell. However, the truth is that, until you know your current soil status, you are just wandering around in the dark in terms of what to do next.

Taking A Soil Sample - Any time that the soil is not frozen is a good time to have the soil from gardens, lawns, flowerbeds or fields tested. A standard soil test will tell you the level of major nutrients such as phosphorus and potassium, the pH, soil type, and the nutrient holding capacity of the soil. Based on these levels, a computer-generated recommendation will tell you how much fertilizer is needed to grow a good crop of vegetables, grass or flowers.

The key factor in taking a soil sample is that it must REPRESENTATIVE of the area you are testing. If you go out and dig one hole and make your sample exclusively of soil from it, you might be in trouble. That may be the absolutely best or worst spot in your landscape. This would lead to faulty results that could lead to the application of too much or too little in terms of nutrients or pH balancing.

So, the best thing to do is to take several small subsamples at many (6 to 10) places around your planting area. Then, thoroughly mix all the subsamples together in a clean plastic pail or bag before you scoop out enough for the sample size needed by the lab. This should give you a good average sampling that will be representative of the entire area.

Another part of being "representative" is to take the sample down to the typical depth of the root systems of the plants you will be growing. For most perennials, this would be around 6 to 10 inches while trees might go a little deeper to about 18 inches. Turfgrass needs to go down to about 6 inches in depth for a sample.

How many samples should you take? Generally, a "sample" will be determined by two factors. One is the crop to be grown. So, if you have perennial beds and borders (or mixed beds or borders), lawn and a small orchard area, you might benefit from 3 different samples. Be sure to label each sample based on its location so that the different recommendations will be easier to apply properly.

The second factor is the type of soil. If you have a high ground area that is very sandy and a lower area that is generally more of a clay type soil, this would call for 2 different samples. Nutrient and pH change recommendations will vary depending on the soil type being tested.

Submitting the Soil Sample - When choosing a laboratory to test your soil sample, you have basically three options.

A. Do It Yourself - There are all kinds of soil test kits out there on the market. Perhaps the best thing to say about them is that you get what you pay for when you purchase one. You might be able to get an accurate result from the kits and you might not. You will never really know. If you do everything exactly according to the directions, you will get a good, general idea about soil pH or soil nutrient levels but that is about all. Most of the time, I suspect people get widely varying results and they don't know enough about soil chemistry to figure that out. As you can tell, I am not a big fan of the home test kits.

B. Private Soil Laboratory - There are private companies that offer soil testing services. These are generally run by people trained in soil chemistry who can take your sample and turn it into reliable recommendations. Often, you can find such companies by doing an internet search.

C. University Laboratory - Every state has at least one Land Grant University which will have an Extension Service office in all (or nearly all) counties of the state. These will offer a service where you bring your sample to the office or mail it directly to the university for analysis. This is probably the option used by most home gardeners.

Related Articles: Soil pH - Acid Soils - Alkaline Soils - Lime - Soil Test

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.

 

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