Don’t Guess – Soil Test!

Soil testing

A soil test can tell you what plant nutrients may be limiting in your soil, and what to add based on the crops you plan to grow. They are also important for measuring soil acidity and determining the need for lime. Remember, a soil test is only as good as the sample collected! Learn how to take a good soil sample and download the guide here.

If there are other labs that we should add to this list, please let us know.

Snohomish Conservation District does not endorse or recommend any soil labs. However, there are several in Washington and Oregon to choose from.

**Make sure the test includes phosphorus, potassium, calcium, magnesium, and boron, as well as a measurement of the pH and lime requirement. Nitrogen availability is very difficult to predict with a soil test and is typically not included.**

I have results back from the lab – now what?

For help interpreting your soil test, start with this guide. For questions about soil test interpretation, or soil quality contact your Farm Planner.

Depending on the lab you use results may be listed as low, medium, or high; below optimum, optimum, or above optimum. An interpretation of “low” or “below optimum” tells you that the addition of nutrients is very likely to increase plant yield. An interpretation of “high” or “above optimum” tells you that the addition of nutrients is unlikely to increase plant yields.

Graph showing the effects of soil pH on the availability of plant nutrients


There are many helpful resources for managing soil fertility, depending on your region and the type of crops you are growing.