What's In Your Soil
When, Why, and How to Test Your Soil
Healthy soil is essential to thriving gardens. If you are just getting your garden started, or you have an established garden that isn’t thriving, soil testing can provide an understanding of the “ingredients” of your soil, so you can use the right recipe to amend, improve and treat for what your soil and plants need.
Soil tests can:
- Help us find out why plants are not growing well.
- Tell us about nutrient levels of nitrogen, potassium, and phosphorus as well as the soil’s pH level which measures whether the soil is neutral, acidic, or alkaline.
- Alert us to the presence of heavy metals including lead; so we can take appropriate precautions.
- Commercial testing can also test for organic matter or other micronutrients.
Where to start to get your soil tested?
One way is to go the commercial soil testing route which is usually more accurate than the inexpensive do-it-yourself soil test kits. The UC Master Gardeners do not offer a soil testing service, but the Master Gardeners of Alameda County does have a resource to find some relatively local soil testing laboratories: “Analytic Testing Laboratories for Home Gardeners”.
We suggest calling several labs and get an idea of costs and timing since commercial soil testing can be expensive. Note that labs vary widely in their final reports; some give detailed results and explain what the numbers mean and how to remediate the soil based on the results. Others provide the numbers but not a lot of explanation as to what the numbers mean or what to do to remediate the soil to fix deficiencies in the soil. All testing labs can provide you with a sample report so you can see what a typical report looks like, how detailed it is, and if it suits your needs.
Links to learn more
We suggest reading the information at these links ahead of calling labs so you have some idea of the key questions you will want to ask.
- Soil Testing and Soil Contaminants:
- Cornell Guide to Soil Testing and Interpreting Results:
- Home Gardens and Lead:
You may want to familiarize yourself with the online resources available from the labs themselves; some are extremely helpful and give you a very good idea of the type of services offered.