How to soil-test a lawn (and when)
Most lawn fertilization recommendations are applied blindly -- without knowing what the soil already has. A soil test takes 15 minutes of sampling work and costs $15--$30 through a cooperative extension laboratory. The result is a profile of pH, available phosphorus, potassium, and organic matter.
Most lawn fertilization recommendations are applied blindly — without knowing what the soil already has. A soil test takes 15 minutes of sampling work and costs $15—$30 through a cooperative extension laboratory. The result is a profile of pH, available phosphorus, potassium, and organic matter that either confirms your program is appropriate or reveals you have been spending money and effort on things the soil doesn't need, or missing things it does.
What a soil test measures
Per Cornell Cooperative Extension, a standard lawn soil test measures:
- pH — the single most important value; affects availability of all other nutrients
- Phosphorus (P) — often adequate or excess in many home lawns
- Potassium (K) — affects drought and stress tolerance
- Organic matter % — indicates soil biology and water-holding capacity
- Secondary and micronutrients (calcium, magnesium, sulfur, iron) — often included in comprehensive tests
Nitrogen is not measured because it is highly mobile in soil and changes rapidly — the test value would not be meaningful.