Moose Lake Star Gazette - Serving Carlton and Pine Counties Since 1895

By Judy Walker
Moose Lake Star-Gazette 

Some dirt on soil testing

Master Gardener Program


Last month I dropped off soil samples at the U of M Soil Testing and Research Analytical Laboratories, and left with a very enthusiastic “Yes!” to a request for information about soil testing. Many thanks to Stephanie Gawtry, Principal Office and Administrative Specialist at the testing lab in St. Paul for her helpful responses!

• About how many soil tests does your lab perform in a year?

Lately it’s been around 12 to 13 thousand samples each year.

• Do you do all the testing there on campus, or do you send some of your testing to other places?

All of our testing is completed on campus in our newly-remodeled, state of the art laboratory.

• I've been gardening for years, and everything seems to be growing just fine. Would I still benefit from having my soil tested?

Getting your soil tested can be a great way to learn about your soil. It will give you exact fertilizer recommendations based on what you’re planning to grow and the measured nutrient levels in your soil. This ensures that you add enough nutrients for your plants without adding extra, which could pollute the environment.  Also, having the pH information can help you decide which plants to grow in the future, since certain plants may grow better in more acidic or alkaline soils.

• Will the test results come with any advice on what I can do differently to get better results in my garden?

Yes, your report will provide fertilizer and liming recommendations for whatever you’re trying to grow. For example, a “Lawn and Garden” report has an option for lawns, vegetable gardens, flower gardens, trees and shrubs and more.  Our “Farm and Field” report details 60 different crop-specific recommendations. There are also written comments that provide additional information.

• How long are test results "good for"? When should I get another one?

A soil test should be good for about three to 4 years, although some clients like to be very exact and will retest every year.

• I have many different raised beds in my garden. Do I need to test each one separately to get the best results?

It depends on how exact you want to be. If the soils have the same origin, and have been treated similarly over time, you can combine the soils and get an average result that will represent all of them. However, if there is one bed that is doing poorly, or has soil that looks or feels very different, we would recommend keeping those areas separate. You may also want to separate beds depending on what you’re growing — for example, vegetable beds vs. flower beds.

• How do I best translate and apply your recommendations to my raised beds (i.e., 100 square feet vs. the smaller square footage of my raised beds)?

To be exact, the pounds of fertilizer you apply will be equal to your actual square footage multiplied by your soil report recommendation (in lbs/100 sq ft), and then divided by 100.

This website can help you determine your square footage if your garden is an unusual shape:

• I have already planted my garden. Can I still modify the soil based on your recommendations?

Yes, you can. A quick-release or water-soluble fertilizer can be added to the surface or side-dressed. Sometimes, if you’re critically low in a specific element you can apply the fertilizer via foliar application. This is commonly done for copper or boron deficiencies.

Visit for instructions on submitting soil samples and guides for understanding the results of your report.


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