The bushel is a critical unit in grain farming. It’s used to describe volume in many contexts, including a crop’s yield per acre, the amount of grain that fits in a truck or bin, and as a fundamental piece of information in grain sales contracts.
But not all bushels are the same.
More specifically, a bushel in Canada is not the same as a bushel in the U.S. — an important piece of information if you’re buying or selling grain across the border.
Since test weights are often expressed in pounds per bushel, using the wrong bushel can result in grain not meeting the test weight required in a contract.
“Depending on what bushel is being used in a calculation, it could impact the outcome,” explains Anh Phan, chief statistician at the Canadian Grain Commission (CGC), in this Wheat School episode.
The British or Imperial bushel volume is equal to 36.369 litres. The Winchester bushel used in the U.S. is around three percent smaller, at 35.239 litres.
But that’s not the only difference.
Canadian bushel weights are calculated using the Avery bushel, which is based off the British bushel volume, but also accounts for grain compaction.
As Phan explains, an Avery bushel weight is calculated using a device called a Schopper condrometer — a metal cylinder with a perforated bottom. A metal puck is dropped on the grain, theoretically allowing more grain to pack in the same volume.
Conversely, a Winchester bushel weight is calculated simply by weighing a specific volume of grain, with only gravity affecting density.
This means the weight of a Winchester or U.S. bushel is slightly lower than the weight of an Avery bushel used in Canada.
For example, No. 1 Canada Western Red Spring wheat with a bushel weight of 60.1 lb/Avery bushel in Canada will have test weight of 56.6 lb/Winchester bushel in the U.S. (see more examples here.)
- British or Imperial bushel — equal to 36.369 litres (or 1.2843 ft3)
- Winchester bushel — equal to 35.239 litres (or 1.244 ft3) and used in the U.S.
- Avery bushel — equal to the British or Imperial bushel, with the effect of compaction. Used in Canada.
To simplify conversions to Avery bushel weight, the CGC maintains charts which account for the different compaction factors of different grains.
Consistent phone calls to the CGC on this topic indicate not everyone is aware of the differences, says Phan, with most callers questioning why they failed to meet contract specifications.
“This so-called confusion hasn’t gone away. I think we need to put more effective information out explaining the difference and what producers should be looking out for when they’re dealing with bushels and bushel weights,” he says.
Knowing that there are different ways of measuring a bushel, his advice is simple: “Know what bushel is being used in the transaction.”
Listen to Phan explain the differences between how bushels are calculated, in this Wheat School episode:
Click here for more for info on the Canadian Grain Commission’s website.