A garden soil test is a good way to determine if your soil is lacking any nutrients, and if there are any other soil related issues you may have such as high salts or pH. The goal is to add enough nutrients to the soil to get a productive and healthy garden, without wasting money and time adding more than you need. Once you know your soil and have a baseline for your garden, testing the soil every 3 years is usually sufficient. More frequent testing may be necessary if you have saline soils, extremely high pH, or other issues.
There are also many commercial labs to choose from, including Stukenholtz in Idaho, and Ward in Nebraska.
- The best time for a soil test is in the spring before you apply any fertilizer.
- Use clean tools. Fertilizer, compost, pesticides, or even grease can contaminate a sample and lead to inaccurate results.
- Collect 10 individual samples from a large garden, or 5 from a small garden, and mix together in a clean bucket to form a composite sample for analysis. This will ensure that your results are representative of the entire garden not just a small portion.
- Sample to a depth of 10 to 12 inches for gardens, and 4 inches for lawns.
- Avoid any unusual areas, or get a separate soil test for these areas. Similarly, be sure to get separate soil tests for any areas requiring special management. For example, that lower garden that has just never produced as well, the corner where you added manure last year, or in your raspberry patch or apple orchard.
All labs will use established laboratory protocols for soils in this region but will display the results differently. Here is an example of what your results from CSU will look like (including fertilizer recommendations).
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