How to test soil

MSU Extension Soil Web pages for Consumers

To get an MSU soil nutrient test: (for contaminant testing click here)

The MSU Soil and Plant Nutrient Lab offers soil nutrient testing services to farmers and gardeners through the local county MSU Extension offices. Some county MSUE offices sell the boxes but you must mail them to the lab yourself, while others provide delivery to the lab. The counties provide various levels of support to interpret the results and to keep them on file, since they are valuable for 3-4 years. Some county offices therefore charge more than the standard lab fees. The lab prefers to receive samples in the prepaid boxes, charging 50 cents extra if you send samples without the box. You must send the standard informational form with your sample. You can pick up the form from your county office or print it here as a .pdf (Acrobat) file. standard informational form.

Go to my county MSUE office web page for contact information

Soil Sampling instructions: Using a soil probe, spade or trowel, and a clean plastic bag or pail, sample in a zigzag fashion throughout a uniform area.

Diagram 1:
How to take sub-samples. Take cores using a soil probe, as shown, a bulb planter or soil auger, or use a trowel or shovel to take a uniform slice from the side of a started hole. Field Soils 8 inches deep, Garden Soils 6 to 8 in. deep, Lawn Samples 3 inches below turf

To get an accurate sample

"Garbage in, garbage out" applies to soil tests; even though the lab does accurate work, good results depend on your taking a representative sample.

	Avoid the edges and any unusual spots in the area being tested.
	If soils have been growing different crops, fertilized differently or if they appear different; darker, coarser in texture, etc., then sample those areas separately.
	Break a large field down into subunits for sampling: the sample area should not exceed 10 acres.
	Take at least 15-20 cores or subsamples to make up your sample.
	Sample as deep as you will be tilling the soil, or use this guide:
	For gardens, 6 inches, for lawns 3 inches below turf, for trees and shrubs 6-8 inches deep.

Diagram 2
Three different soil tests for three different crops.

Vegetables, 20 random cores, or sub-samples from the area combined to make one soil test.

Lawn, 20 random sub-samples from the area combined to make one soil test.

Perennials, 20 random sub-samples combined (Thanks to St. Clair County MSUE for the diagrams showing sampling patterns appropriate for different consumer crops).

To submit the sample

Combine cores for one crop/area into the plastic pail and mix thoroughly. (Dry, or at least partially dry wet samples so you can really mix them, and throw out clumps of grass roots, wood or stones).

Fill a soil sample box obtained from your county MSUE office with the dry sample, OR package about 2 cups of soil in a container such as a sturdy zip-type bag. Your name and sample name or number should be clearly marked on the container, to link it to the informational form. Don't write anything else on the container, but make sure your address and other information is on the form. Send to the lab, or take to your MSU Extension office, or to a retailer participating in soil testing programs.

Fill out one form for up to 8 samples from the same address. You can choose the standard soil test or additional cost options. Package forms and samples together, securely for mailing, and send them to the soil testing lab address on the form. If you do not have the prepaid sample boxes, include your check or money order to the soil lab and remember to add $.50 for each sample that is not in one of their boxes.

The post office has flat-rate boxes you can pick up locally or order free online at http://www.usps.com/ for easy mailing of samples regardless of weight. One or two samples in baggies will fit in the small flat-rate box, for which postage is currently $4.95. Fourteen of the standard soil lab boxes will fit in the medium postal flat rate box.

Frequently asked questions at the MSU Soil Lab

Other labs serving Michigan

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This site was last updated 11/16/09

Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, marital status, or family status. Feedback on this site should go to Jennie Stanger, stanger@msu.edu