Agriculture and Forestry: The Why and How of Soil Testing

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The Why and How of Soil Testing

Fertilizers remain the major item in the production cost of most crops. Proper use of fertilizers will assure maximum marketable yields. Excessive use of fertilizers must be avoided to protect the environment and assure optimum returns from each fertilizer dollar. A good soil testing program is a valuable tool in determining fertilizer requirement for efficient and economic crop production on an individual field basis.

The Need: Why Soil Test? Soil testing is one of the best ways for farmers to assess the fertility of their land and decide how much and what type of fertilizer and limestone must be applied for maximum crop yield. Soil testing can help overcome such problems as:

low yields due to lack of fertility,
acid soils,
using the wrong fertilizer, and
using more fertilizer than necessary for maximum yield.

Soil testing should be carried out regularly (usually once in a rotation) and never less than once every four years. The following is a guide to getting soil test results.

When to Sample Soil samples may be taken at any time but remember the following:

Time is often too short when sampling in spring.
Fall sampling assures your results back long before planting.
Early fall sampling gives you results in time for fall liming.

Assemble the Necessary Tools In taking a soil sample, care must be taken to get a uniform core of soil. The tools you will need are:

a clean pail - for mixing
a soil probe
a shovel or spade

Soil Probe Photo Note that the soil probe is the best sampling tool, especially in sod fields (soil probes are available from the Soil and Feed Lab and the District Offices).

Size Up Your Field One sample should be taken from each field or area which appears uniform and has a similar cropping history.

Sections to avoid and sample separately are:

Areas of high slope or excessive erosion.
Large poorly drained or low lying areas.
Areas of different cropping patterns.
Areas having different lime, manure or fertilizer treatments.
Large fields should be divided into subsections no greater than 10 ha. (25 acres) and sampled separately.

Take a Representative Sample As there are slight differences, even within uniform fields, take soil from 10-20 different places in the field. The depth to which the samples are taken is usually 15-20 cm. (6-8 in.) or more if you are using deep tillage. If established forages are being sampled, the sampling depth should be between 10-15 cm. (4-6 in.). Soil should be placed in a clean pail and mixed thoroughly. Submit about 500 gms. (approximately 1/2 pint) of soil for analysis. Use soil sample bags or boxes (No Charge) available from District Agricultural Offices or the Soil and Feed Lab.

Fill out the Information Sheet In order to obtain a good fertilizer and lime recommendation, all information about the field history and cropping is necessary. The information questionnaire should be filled out completely and placed with the sample.

Package Carefully and Send for Testing Samples may be brought or sent to:

P.E.I. Soil and Feed Testing Lab
P.O. Box 1600
Research Station
Charlottetown, PEI, C1A 7N3

Samples may also be left at your nearest District Agricultural Office.

Turn-Around-Time of Samples Expect to wait two to three working days for sample analysis to be completed. Three different packages are available for sample analysis. Package 1: Regular sample analysis, which includes pH, organic matter, phosphate, potash, calcium and magnesium plus fertility recommendations based on the crop to be grown. Package 2: Micronutrient analysis. Samples are analyzed as in Package 1 plus micronutrient determination (copper, zinc, boron, iron and manganese). Package 3: Lime Requirement Determination. Sample analysis includes both Packages 1 & 2 plus buffer pH, cation exchange capacity and percent Base Saturation.

For More Information For more details, soil bags or boxes and general information, contact the Soil and Feed Laboratory at (902) 368-5628 or your District Agricultural Representative.