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Taking a proper grain sample

When sending grain off as a sample or having a seed lot tested, it’s critical to take a representative sample, according to Barry Little of 20/20 Seed Labs Inc.

Having accurate information about the grain in the bin will help farmers (and buyers) make better decisions.


One reason accurate sampling is so important is that grain will segregate. “This is the separation of shapes, weights, and size that happens after the discharge of the grain from the auger or conveyor or any other movement of it into a static state,” says Little.

“We’ve all watched a bin or a truck be filled with grain and have seen different weights, sizes, or shapes of grain or impurities and contaminants go to different places.”

The way the grain segregates will depend on the shape of your storage.

“Secondly, a round bin, a square bin, a hopper bottom, and a rectangular truck box will all have an impact on where some of the segregated product will end up.”

Once grain has segregated itself in the sides, middle, corners, and other places, these different groups will exit the bin or truck at different points and intensities. This reinforces the need for sampling at multiple locations.

Little has seen the significant benefits from “consistent, intensive seed sampling rules verses the lax and inconsistent grain sampling equipment and techniques currently used.” Little’s job includes providing training in proper use of equipment, sampling techniques, maximum lot sizes, sampling intensity, and sample preparation for seed testing lab submission.

Stream sampling

If done properly, Little says, “Sampling your grain in the bin with a probe or stream sampling from the truck or the end of the auger are very good methods.”

Stream sampling is a good way to get a representative sample. Little says, “The most important factor is to take a large number of primary samples to get a clear picture of the whole lot.”

According to Little, if everyone followed rules established by the International Seed Testing Association (ISTA), procedures would be a lot more involved. For example, each 30 ton lot would have been sampled at least 40 times. “This would be okay if you’re taking stream samples from the end of the auger every couple of minutes, but probe sampling does seem overwhelming when you’re in the top of a hopper bin pushing a 12-inch long probe into your wheat 40 times.”

Ordinarily, sampling is more representative from a stream than from a bin using a probe, due to the challenges of accessing all areas of the bin.

Grain probes

Once you’ve got the grain in the bin and it’s too late to take a stream sample, there are several kinds of grain probes to choose from. Each has its own set of pros and cons depending on its application, container type, and use mode.

“The most obvious parameter is probe length, but there are also different tube diameters. And the slot opening needs to be big enough for the grain and contaminants being probed,” says Little. “Other typical differences are compartmentalizing, non-compartmentalizing, and spiral opening.”

A partitioned probe has openings along the length of the probe, to allow farmers to sample from different depths of the bin.

“In theory, you should be able to reach all parts of the container with your probe to help ensure you’re getting a good cross-section of all grain from all parts of the bin or container,” said Little. “If your probe is four inches long and your bin is 10 feet high, you have a problem.

Representative samples

“Once you’ve collected all your primary samples, whether that’s five or 40 samples, you need to ensure they’re thoroughly mixed together to form the composite sample before sending it to a buyer or away for testing.

“If the composite sample is fairly small, it might be fairly simple to mix in the bottom of a pail by hand or using a stick. On the other hand, when many primary samples have been taken, you might end up with one or two five-gallon pails. In that case, if the grain isn’t mixed repeatedly using good technique, segregation might have resulted.”

Once you’ve got your sample and are ready to send it off or take it to town, Little says, “it’s also important to always retain a duplicate sample after mixing for further testing at a later date.”

Little advises having a plan that includes the number of samples you will take, a randomized method of covering all parts of the bin or container, proper equipment, a large enough collection container, and clean equipment. †

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