Free · Land-grant university labs · County Extension
Know your soil before you add anything.
A basic soil test from your state's university lab often costs less than a bag of fertilizer. Pick your state to see the lab, how to send a sample and how to reach your county Extension office.
CDC says no safe blood lead level in children has been identified, and even low levels can harm learning and development.
CDCEPA says over 400 ppm lead means do not use existing soil for food gardening; use containers or raised beds.
EPAUniversity of Maryland says adding more of a nutrient already rated optimal or excessive will not improve plant growth.
UMD ExtensionSoil labs by state
Soil testing labs in every state
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Why it matters
Guessing costs more than testing.
Lime, fertilizer and compost all change soil chemistry. Without a test it is easy to add phosphorus a lawn already has plenty of, or to lime soil that is already alkaline. Land-grant university labs give recommendations tuned to local soils and crops.
Your county Cooperative Extension office is the shortcut. Most hand out sample bags and forms, explain results, and in many states will ship samples to the university lab for you.
Guides
Plain answers, sourced
How to take a soil sample for a lab test
Learn how to take a clean, representative soil sample for a lab test, from choosing spots and depth to drying, labeling, and sending it in.
Read →University soil labs vs. private labs vs. home kits
How university soil labs, private labs, and home kits compare on accuracy, recommendations, lead testing, and the best fit for home gardeners.
Read →How to read a soil test report
Learn how to read a soil test report, from pH and lime to nutrient ratings, units, and optional lead tests, so you can make a clear plan.
Read →Soil pH and lime: what your test is telling you
Learn what soil pH, buffer pH, and lime recommendations mean, when to add lime, how much to apply, and when liming can backfire.
Read →When to test soil, and how often
Learn the best time to test soil, how often to retest lawns and gardens, and when to ask for lead or flood-related checks before planting.
Read →Testing garden soil for lead and other metals
How to test garden soil for lead and other metals, choose the right lab, collect samples, understand results, and garden more safely after.
Read →Featured partners