Smart Gardening: Soil Tests

I’m Gary Heilig horticulture educator
from Michigan State University Extension. Welcome to smart gardening. Today we’re going to talk about soil testing.
Plants require specific elements which we call nutrients in order to grow and produce high
quality fruits, vegetables, and flowers. They include nitrogen, phosphorus, and
potassium which are the main ingredients in a
balanced fertilizer mix, but also calcium, magnesium, boron, chlorine, sulfur, and others are required
for good plant growth. The level of nutrients in a particular
soil can vary widely depending upon the type and history of that
soil. So, a smart gardener will conduct the soil test to determine the
crops nutrient needs thereby avoiding over or
under fertilization. Applying the correct amount of fertilizer can save money, and will help protect
Michigan’s water resources by reducing the amount
excess nutrients that may runoff and end up in rivers lakes and streams. A gardener’s ultimate goal should be to
grow healthy plants without depleting the soils nutrients or
causing pollution. Soil testing is one of the ways to
achieve this goal. Michigan State University Extension
offers a soil test kit that can be obtained from the online
Michigan State University Extension bookstore. Once at the site, select the soil test
kit self mailer icon or type soil test kit in the search
box. Use a spade, hand trial, or soil sampling probe to collect 10 to
20 random samples to a depth of 3 to 7 inches from the lawn or garden area. Each of these
sample should be approximately 1/2 cup. If the soil is wet, let it air dry
naturally before mailing. Mix all the samples together in a
clean container, and place about 1 cup into the plastic
bag and seal it tightly. Don’t overfill the plastic bag or pour
extra soil into the envelope. Fill in the information on the self-mailer form, and be sure to print clearly, and place it
in with the sample in the postage-paid
envelope and drop it into the mail. The results will be emailed to you in a
few days. After receiving the results go to, and select the “Understand Your Soil Test Results” bar. Then enter the soil test results code
received in your email. This is a code for your
personalized recommendations. There’s a page to enter nutrient level information, and the area of your garden. The nutrient
recommendations are listed as actual pounds needed for the area you
listed. Since various fertilizers contain
different levels of nutrients, some simple math will be required to
determine how much of a particular fertilizer should be applied. For example, if three
pounds per thousand square feet of actual nitrogen are needed and you plan to use urea as the
source, 6.5 pounds would be required. That’s three divided by .46 which represents the percentage of
nitrogen in the bag. If dried blood meal was selected as the nitrogen source, 23
pounds per thousand square feet would be needed to supply the same amount of nitrogen.
Since dried blood is only thirteen percent nitrogen. Once your garden nutrient needs are
calculated, you are ready to begin the planning for an environmentally friendly and
smart garden. If you have questions or need further assistance call the garden hotline 1-888-676-3464. I am Gary Heilig, thanks for joining me on smart gardening.

1 thought on “Smart Gardening: Soil Tests

  1. I assume I would do the test after I add my compost in the spring before planting, since the compost will change the levels ? I am building all new beds, some of them double dug, which at this point just have the original soil in them until I can get the cities compost in the spring.

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