What causes low protein soybeans?

Soybeans grown in Illinois have more protein than beans grown in North Dakota. It appears as though protein content is connected to latitude.

However, soybean experts don’t fully understand how factors like heat units, moisture and geography affect protein content.

“We don’t know that yet,” said Elroy Cober, Agriculture Canada soybean breeder in Ottawa.

Daryl Domitruk, Manitoba Pulse & Soybean Growers director of research and production, gave the same answer: we don’t know.

“There’s a gap in our understanding, as to what the major contributing factors would be,” he said. “Is it simply my variety selection? No, it isn’t. Is it inoculation practices? Maybe. Is it how much drought stress or moisture stress the plant may be under? Maybe.”

To answer those questions, Cober and others have a research project on the Prairies. They have planted soybean varieties with low- to high-protein content and will monitor how the varieties respond to a range of agronomic and environmental conditions at a number of sites in Western Canada.

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