Common Questions

If you don't find an answer to your question below, please contact us at (517) 355-0218 or send an email to spnlab@msu.edu

Why should I soil test?

  • Soil testing is an important diagnostic tool to evaluate nutrient imbalances and understand plant growth.
  • The most important reason to soil test is to have a basis for intelligent application of fertilizer and lime.
  • Testing also allows for growers and homeowners to maintain a soil pH in the optimum range (6.0-7.0), which keeps nutrients more available to the plant for growth.
  • Protection of our environment - We cannot afford to pollute our surface and ground waters by indiscriminate application of phosphorous or nitrogen fertilizers, for example.
  • Cost savings - Why apply what you don't need? Soil test results provide information about the soil's ability to supply nutrients to plants for adequate growth, and are the basis of deciding how much lime and fertilizer are needed.

What is being tested in a soil sample?

  • The regular soil test includes determination of soil pH, available phosphorus, potassium, calcium, and magnesium levels as well as recommendations for lime and fertilizer. Other soil tests are available at supplemental costs, such as, organic matter, zinc-manganese, etc.

How do I know if the test results are accurate?

  • The lab takes various quality control measures to ensure the accuracy of results. Soil with predetermined nutrient levels is tested every 20 samples to provide an accuracy check.
  • MSU recommends testing soil every 3 years. If recent results are not consistent with past results, notify your county MSU Extension agent or the lab within one month to rerun the questioned test.

Why doesn't the regular MSU soil test include nitrogen analysis?

  • Soil nitrate levels are the best indicator of nitrogen availability. Because these levels fluctuate widely depending on rainfall and soil temperature, the best time to take soil nitrate samples in while the crop is growing. within two weeks of supplemental nitrogen applications.
  • A soil sample taken months ahead of this time will not provide an accurate measure of the nitrogen available to the plants.

How does the lab make nitrogen recommendations?

  • Nitrogen recommendations are based on the past and present crops grown plus the yield goal for the crop to be grown.
  • Less nitrogen is recommended when the previous crop was a legume, because they add nitrogen to the soil.

Where can I get my soil samples tested?

  • Take the soil sample to your county MSU Extension office, located in your county seat.
  • Bring the sample directly to the MSU Soil and Plant Nutrient Lab, room A81 (basement), in MSU's Plant and Soil Science Building, which is located on the south west corner of Bogue and Wilson.
  • Mail it directly to us at:
    Soil and Plant Nutrient Laboratory
    Department of Plant, Soil and Microbial Sciences
    Plant and Soil Sciences Building
    1066 Bogue Street, Room A81
    East Lansing, Michigan 48824-1325

How soon should I receive test results?

  • You should receive test results in about two weeks. The analysis take 3 to 5 working days from the time the lab receives the samples.
  • The results are then mailed to your county MSU Extension agent for interpretation.
  • Remember MSU recommendations are in pounds of nutrient needed, not pounds of fertilizer to be applied!