Consideration for Market Gardeners: Soil Sampling - Frequently Asked Questions

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 Why bother to do a soil sample?
A soil sample provides basic information about a particular field, such as pH, texture and organic matter, as well as soil nutrient levels at the time of sampling. Soil testing helps growers track changes in soil fertility in their fields and can be the basis for fertilizer management and application decision making.

When is the best time to do a soil sample?
Soil sampling should be done either in the spring, prior to seeding, or in the fall after soil temperatures drop below 5C.

Things to remember when sampling

  • Field vegetables can draw nutrients from up to a depth of 24 inches (60 cm). Soil samples should be for 0 to 12 inches (0 to 30 cm) for most crops, however producers may decide to sample only for the depth of cultivation. Deeper rooted or perennial crops might require information for a deeper soil profile, therefore a soil test should be done for 0 to 12 and 12 to 24 inch (0 to 30 and 30 to 60 cm) samples.
  • A soil sample should be a representative sample of the entire field and should be collected from a wide range of locations across the field.
  • When sampling, avoid obviously unusual or abnormal locations. This would include low spots, eroded knolls, trashy areas, field margins or parts of the field where high levels of manure have been applied.
  • Keep samples free from contaminants.
  • Once a sample has been collected, keep it cool and ship it immediately.
Special considerations for market gardeners
Most market gardeners produce a diverse assortment of vegetables on a small area, and as such the crops may vary a great deal in the amount of fertilizer that they require. A soil test will provide general recommendations for fertilizer application, based on the field average. The soil test can be used as a baseline for any decisions. Growers should consider each crop separately when making fertilizer application decisions. The decision-making process should also include careful consideration of field cropping history and prior crops in the rotation, fertility demands of the crop, as well as the various other management practices that might be included in the season.

More information
More information on soil sampling can be found in the following document.
Soil Testing and Sampling Guide

Prepared by Robert Spencer, Ag-Info Centre, Alberta Agriculture and Forestry

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For more information about the content of this document, contact Robert Spencer.
This document is maintained by Marie Glover.
This information published to the web on April 21, 2004.
Last Reviewed/Revised on May 18, 2017.