February 9, 2016

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How to Sample: Farm/Commercial Horticultural Field

Soil tests can be no better than the sample. Therefore, proper collection of the soil sample is extremely important.

Divide the field into uniform areas

Each area should have the same soil color and texture, cropping history, and fertilizer, lime and manure treatments. One sample should not represent more than 20 acres on level, uniform landscapes, or 5 acres on hilly or rolling land.

Sample each area

Within each area collect 15-30 subsamples (cores, borings, or spade slices) in a zig-zag pattern throughout the designated field area. The more variable the soil, the more subsamples should be combined per area sampled. Scrape off all surface residue from the subsample site. Sample to a depth of 6-8 inches (plow layer) for cultivated crops, or 3 inches for pasture or sod fields. Sample row crop fields between rows, except for ridgetill plantings. Where RIDGETILL is used, take the sample to a depth of 6-8 inches on the shoulder of the ridge, avoiding the starter fertilizer band. Also avoid sampling dead or back furrows, terraces, old fence rows, lime or fertilizer spill areas, headlands, eroded knolls, low spots, or small saline areas. Sample at least 300 feet away from gravel or crushed limestone roads because their dust changes soil pH.

Mix the subsamples

Mix the subsamples thoroughly in a clean plastic pail, and fill the sample box or bag to the fill line (1 pint). If the samples must be taken wet, they should be dried before being mixed and submitted to the Laboratory. Do not exceed a drying temperature of 97F, and do not use a microwave unless only the nitrate test is requested.


How to Submit:

Download/Print the Soil Sample Information Sheet

Fill out the information sheet as completely as possible so that accurate recommendations can be given. Keep a copy for your records. Place the sample in a tightly sealed container or bag (e.g. a clean disposable food container or bag). If you have trouble printing the form, send us an email to request a printed form.  See “About Us” for contact information.


For the regular test (which includes P, K, pH and organic matter);

$15 per sample for agricultural samples

Prices for testing are also listed on the Information Sheets. Enclose a check payable to the University of Minnesota for all services requested. Do not send cash. The University of Minnesota will not be responsible for cash sent through the mail. The sender pays the postage.

Sending Soil Samples


  • Mailing

Enclose the information sheet along with a check made out to the University of Minnesota and mail to:

Soil Testing Laboratory
University of Minnsota
1902 Dudley Ave.
St. Paul, MN 55108

  • Delivery

The sample can also be brought to the laboratory. Fill out the information sheet along with a check made out to the University of Minnesota and bring to:

Room 135 Crops Research Building
University of Minnesota
St. Paul Campus

(See About Us page for directions)

See also: