Ask an Expert is happy to help you with soil testing.
Soil testing laboratories are the best way to get an accurate picture of your soil. So, choose a laboratory to assist you. There are a number of alternatives in this Extension Service publication. Click here.
The website of the laboratory you choose usually provides information on taking a sample and shipping it. Or give them a call. One to two cups of soil should be enough for the standard garden nutrient tests (pH, nitrogen, phosphorus, and potassium). A plastic container that will not break in shipment will be fine.
Be sure to provide the requested information on your site to the laboratory, and ask for fertilizer recommendations to fit your particular situation.
Testing should take just a few days. Results can be available on the web, by fax, by email, or by postal mail.
For more information, you can call the Marion County Master Gardeners at 503-373-3770 (Monday through Friday-- 9:00 am to 5:00 pm).