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How to collect a soil sample at your home.
Since only a small portion of the soil is used for testing, it is very important that the sample be representative of an area.  For a standard soil test, take several samples from each area of your yard (front yard, shrub bed, garden, etc.),. For large areas, 5-8 cores are needed, but for narrow shrub or flower borders, 2-4 cores will do the job. Mix all of the samples together in a clean pail or bucket to get your representative sample or "average" soil for your yard.

If you are targeting a problem area, you can restrict your sampling to the problem area only.  (Instructions adapted from Purdue Ext. “Collecting Soil Samples for Testing” HO-71-W)
  • Remove surface debris, such as plant residues, mulch or turf thatch, from the soil before inserting the soil probe, spade, or trowel.
  • Sample gardens and shrub and flower beds to a depth of 6-8 inches.
  • Sample turf areas to a 3-inch depth.
  • Sample tree root zones to 8-12 inches or deeper.
  • Sample row crops (in gardens) between the rows to avoid fertilizer bands.
  • Sample front and back yard separately if they have been managed differently or contain different types of fill soil.
  • Dry samples at room temperature. (Do not use artificial heat.)
  • Break up any lumps and remove all stones, debris, grass, etc. When dry, mix well and eliminate clumps.
  • Bring ~2 cups of soil to the SWCD in a clean container for testing.
For complete instructions, view the Purdue Extension Collecting Soil Samples for Testing Publication here. 

Nutrients & Measurements (pH)

  1. Optimum pH for gardens: 6.0-7.0;  pH for turf: 5.5-6.5
  2. Phosphorus for garden: 20-40; Much less for turf or anything with permanent roots
  3. Potassium, magnesium, and Calcium: varies depending on CEC for soil.
  4. CEC: Cation Exchange Capacity- soils ability to hold positive charged particles like K, Mg, and Ca; good levels are between 7 and 15
Source: https://extension.umaine.edu/gardening/manual/soils/interpreting-soil-tests/

 Organic Matter (OM)

  • OM levels are ideal at 5-8%,
  • If OM levels are below 2-3% nutrient and water holding capacity become limited and may not support plant growth;
  • High OM (10%+) can cause wild fluctuations in nutrient availability, especially nitrogen