Soils and Composting: Soil Testing

Soils and Composting | Soil Testing | Soil Type | Soil Improvement | Composting


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Taking a soil sample.


Why Is Soil Testing Important?

Plants differ with respect to their soil pH and nutrient needs. Soils vary considerably in their capability to meet a plant’s nutritional needs depending on factors such as soil parent material, soil texture and structure, the amount of organic matter, biological activities, regional climate, and current growing conditions. Taking a soil test and using the recommendations that come with it will help plants receive adequate amounts of nutrients needed for plant growth. Other benefits, such as minimizing fertilizer runoff into the environment and cost savings from applying only what your plants need, are also good reasons for taking a soil test.

Soil Sampling

The results of your soil test will be only as good as the sample you collect. Follow the instructions from the soil testing laboratory you are using. Failure to take a soil sample according to the laboratory specifications is likely to result in inappropriate recommendations for your garden or yard.

Find out more about soil sampling and reasons for taking a soil sample by reviewing:

– Note: Soil testing laboratories in this publication are relevant for the Ohio area. To find a soil testing laboratory from your local region or state, type in your state and soil testing laboratory in a search engine, or find out if your local university has a soil testing laboratory.

Comparing Store-Bought Kits vs. Professional Services

Many garden centers have soil test kits that you can buy. Should you use a store-bought kit or a soil testing laboratory? Compare the advantages below:

Advantages of store-bought and laboratory soil tests.
Store-bought soil testing kits Professional soil testing laboratories
  • They are often inexpensive (provided you use your kit more than once or twice).
  • They usually provide a very general indication of your soil pH and fertility status.
  • The results are much more accurate. The soil pH is accurate to within one tenth of a pH unit, and nutrient results are measured in parts per million or pounds per acre.
  • Your soil sample is handled by professional staff trained to routinely analyze these types of samples.
  • Soil fertility and pH tests are generally modestly priced. Remember, you will need to purchase replacement chemicals for home testing kits as they expire.
  • You will receive recommendations specific to the type plant you want to grow. The recommendations are based on the latest university research.
  • If you need further assistance or have questions on your laboratory report, an Extension agent or other university personnel can give you follow-up advice. Manufacturers of home testing kits may not offer this service.

There are more accurate kits available through such companies as Hach and LaMotte but they may be expensive. If you are determined to use a home testing kit, we suggest you collect a sample, thoroughly mix it, and divide it into two sections. Test one with your kit and send the other half to a professional laboratory. If the results and the recommendations that come back from the laboratory are similar to those you have obtained with the home testing kit, continue to use your home testing kit.

A summary of research evaluating the accuracy of five commercially available soil test kits can be seen at:

Soil Testing Laboratories, Interpretations, and Recommendations

Each soil laboratory has its own tests, interpretations, and recommendations for the soil samples it analyzes. Use the following resources to find a soil testing laboratory near you: