Facts for Farmers, 13 of a series

Taking a representative sample

Facts on taking a representative sample

Your most valuable two pounds of grain

Your most valuable two pounds of grain is the sample that is used to determine the grade and protein level for the rest of your grain. The quality of grain from several areas of an apparently uniform field can vary greatly, both in grade and protein level. This means that as you harvest, grade and protein can vary from truckload to truckload. As a result, the quality of your grain can vary both within a bin, and from bin to bin.

Equipment used in the grain handling industry copes with variable quality by taking continuous samples. You can do the same on your farm. Here is a simple method for getting representative samples of your grain without using expensive specialized equipment. Contact your provincial labour department for health and safety information on the use of grain augers.

Sampling your bin

You will need four identical pails. They should each hold at least 20 litres (four gallons). Label two of them A and B. You will also need a tin cup or scoop.

Step 1

As each truck load is emptied into the bin, take cupfuls every 30 to 60 seconds from the sides and the center of the grain stream. Empty the cupfuls into pail A. Sample enough grain so that when the truck is empty, the pail is about three-quarters full.

Step 2

When the truck is empty, mix the contents of pail A thoroughly by hand. Place two empty pails of similar size side by side on the floor with the sides touching. Pour the contents of pail A down the center where the pails touch so that each pail will receive about half the sample. The contents of one of the pails can be poured into the bin. Repeat the process with the contents of the remaining pail until about four pounds (two kilograms) remain. Pour the four pounds into pail B.

Step 3

Repeat the procedure for each truckload that is emptied into the bin.

Step 4

When the bin is full, thoroughly mix the contents of pail B by hand. How much of the sample in the pail you keep will depend on your needs. Keep in mind that for most purposes you will need a one-kilogram (two pound) sample. (refer to "Sampling your whole crop")

Step 5

Place the sample in a bag or sealed container. Label it to identify the bin it represents. You may want to make up some one kilogram samples at this point so they are ready when you need them. You now have a good representative sample of the grain in the bin.

Sampling your whole crop

When you reach step 4, you can make a composite sample of your whole crop. All you have to do is take one kilogram out of pail B for each 1,000 bushels in the bin and put it in a separate pail labelled C. Do this as you reach step 4 with every bin you fill. Then mix pail C thoroughly by hand. This should give you a good composite sample of your entire crop.

Summing up

When it's time to market your grain, having dependable samples can prevent nasty surprises. It can also help you decide if you are better off selling your grain by the truckload, by the bin, or by making a deal for all your grain. Remember: the keys to accurate sampling are to sample continuously, and mix the samples thoroughly before you divide them.

Want to know more?

Call: 1-800-853-6705
Fax: 1-204-983-2751
Email: contact@grainscanada.gc.ca

Related information:

The Canadian Grain Commission offers a grading service to producers. For a fee we will give the grade, dockage and moisture content for any sample sent to any of our offices. The more the sample is representative, the more consistent and accurate the grading results will be. Other tests are also available. Contact: Prairie Service Centres or Regions.

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