Soil Testing

Soil tests can save homeowners money and improve growing results by helping accurately determine fertilizer rates and the need for soil amendments, such as compost. The Lewis and Clark County Extension Office can assist with sampling advice and tools, mailing samples, and interpreting results.

Collecting a sample

• Remove any mulch or lawn thatch before collecting your soil samples.
• Collect samples from multiple areas around your yard or garden.
• Soil samples are best collected using hand probes or augers (available at the Extension Office) or bulb planters to obtain the same amount of soil from each depth and location.
• Collect soil to a depth of 6 inches.
• The office needs a quart size bag full of soil (roughly about 2 cups).
• Samples may be collected at any time, but it is best to wait at least two months after fertilization to give the fertilizer a chance to dissolve, disperse and be used by plants. If you take the sample in the fall, keep in mind that you will have more available nitrogen in the spring along with other nutrients than what your analysis indicates.

Sending samples for testing

• The Extension Office uses Midwest Laboratories for soil analysis. Results generally take about 10 days and are sent via email unless requested otherwise.
• Soil Samples are $20 for a Basic Sample:
  • Organic matter, Nitrogen, phosphorous, potassium, soil pH, magnesium, sodium, soluble salts, excess lime.
• Soil Samples are $30 for a Complete Analysis, including vital plant micronutrients:
  • Organic matter, nitrogen, potassium, phosphorous, soil pH, sodium, sulfur, zinc, manganese, iron, copper, boron, soluble salts, cation exchange capacity, and excess lime.
• We only accept Cash or Check (made out to Lewis and Clark County Extension).

Reading the results

• These guides from MSU will prove very helpful in understanding your results:
  
  • Soil Test Quick Interpretation Guide
  • Home Garden Soil Test Ful Interpretation Guide
  • Soil Test Interpretation Guide for Agriculture
  • Soil Fertility Basics
• It's also very helpful to discuss the findings with your local Extension Agent. They can not only help you interpret the results, but can calculate soil amendments and make recommendations to improve the life of your soil.

Home Garden Soil Testing & Fertilizer Guidelines

Interpretation of Soil Test Reports for Agriculture

Soil Sampling Strategies

The U.S. Department of Agriculture (USDA), Montana State University and the Montana State University Extension Service prohibit discrimination in all of their programs and activities on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital and family status. Issued in furtherance of cooperative extension work in agriculture and home economics, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, and Director of Extension, Extension Service, Montana State University, Bozeman, MT 59717