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Smart gardeners get the dirt on soil testing

Testing soil every three years helps you accurately apply fertilizers to your lawn and garden and helps avoid over-use of nutrients that can become a powerful pollutant to Michigan’s natural resources.

Plant scientists know that lawn and garden plants require 18 nutrients for healthy, productive growth. Your lawn and garden “soil environment” is a reservoir that houses these nutrients, providing the platform for plant roots to acquire them. Understanding each individual plant’s needs and the type of soil you have is the first step in properly managing soil fertility.

Often our lawn and garden soils are rich and productive, needing little or no enhancements. Others may be poor soils or depleted, needing to be replenished. Approaching plant care without conducting a base-line soil test may put gardeners at the risk of over fertilization. This can not only can have negative effects on plant growth and create an imbalance in the soil environment, but it can also lead to pollution of our local water resources.

Michigan State University Extension provides an easy-to-use soil test kit that can be obtained online from the MSU Extension Bookstore or from your local county MSU Extension office.Soil test mailer

The Home Lawn and Garden Soil Test Mailer can be used to process any type of home soil sample, such as lawn, vegetable garden, tree, shrub, flower, and tree or small fruit. Based on your soil test results, you will receive a custom fertilization program to meet the needs of your plants and safeguard the environment. The cost of this mailer is $25 plus shipping and handling fees. This mailer may also be available for pick-up at your local MSU Extension county office for $25.

Why should I soil test?

  • Know your soil. Soil testing is an important diagnostic tool to evaluate nutrient imbalances and understand plant growth.
  • Understand. The most important reason to soil test is to have a basis for intelligent application of fertilizer and lime.
  • pH. Testing allows homeowners to adjust soil pH to the optimum range (6.0-7.0), which makes nutrients more available for plant growth.
  • Protection of our environment. Avoid contaminants that can enter our surface and ground waters by over-application of phosphorous or nitrogen fertilizers.
  • 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 will I find out from my soil sample?

Home Lawn and Garden Soil Test Mailer results will determine your soil type, pH, level of organic matter and provide you with a reading for nutrients including phosphorus, potassium, calcium and magnesium. The results will also provide a recommendation for nitrogen and will determine how much lime should be applied based upon the type of plant you specify.

Soil probe
Soil probe used for taking soil samples. Photo credit: Rebecca Finneran, MSUE

How long before I receive my test results?

You should receive test results in about two weeks. The lab analysis takes three to five working days from the time samples are received. Remember, MSU recommendations are in pounds of nutrient needed, not pounds of fertilizer to be applied!

Your results will also include an area calculator that helps you determine how many square feet you need to apply fertilizer.

How do I take a soil sample?Mailbox. Photo: Mary Wilson

  • Determine which one lawn or garden area you would like to test.
  • Using a spade or trowel, collect 10 random soil samples from the area and place in clean pail.
  • Each sample should be a slice of soil as deep as the plant roots go (3 to 4 inches deep for lawn; 7 inches deep for gardens and all other plants).
  • Remove plant debris, roots and thatch from the sample.
  • Combine the 10 random samples in the pail, mix thoroughly and remove approximately 1 cup of mixed soil. If the soil is wet, spread it on paper and allow it to air dry overnight before filling the sample bag. Do not use artificial heat as it will skew test results.
  • Fill the re-closable plastic bag included in the Soil Test Mailer with your dry soil and seal carefully.
  • Place bag inside the white, postage-paid envelope and put in your mailbox for pick up.

Starting from the “ground up,” MSU Extension’s horticulture educators are embarking on a new campaign to help folks become “smart gardeners.”  Launching this effort, MSU Extension horticulture educators will be presenting smart gardening in a variety of ways at two public shows in Michigan.  The Novi Cottage and Lakefront Living Show on Feb. 21-24, and the West Michigan Home and Garden Show on Feb. 28-March 3 will host a variety of free seminars, informational booths and be the site to “ask the experts” from MSU Extension about your gardening questions.

For more information on a wide variety of smart gardening articles, or to find out about smart gardening classes and events, visit www.migarden.msu.edu.

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