Prairie farmers receive mixed signals on boron use

A U.S. agronomist says prairie soil likely needs more boron, but Canadian research tells a different story

Listening to Neal Kinsey is fantastic.

Kinsey, a soil fertility expert, speaks passionately about soil, agronomy and nutrients, but as a bonus he has a unique accent. He’s from southern Missouri and his accent is a combination of U.S. South and the Midwest. His pronunciation of “eye” sounds a lot like “ahhh,” and copper sounds like cawhper.

Kinsey’s soothing voice was a welcome sound at CropConnect, an agriculture conference held in Winnipeg last month, but most of the growers in his session were more interested in his thoughts on micronutrients.

Kinsey, who runs Kinsey Ag Services in Charleston, Missouri, has provided soil fertility advice to farmers in more than 75 countries.

In Winnipeg, he dedicated most of his talk to boron, a micronutrient that may affect the nutrient uptake, seed size and yield of many crops.

Most government and commodity group websites say western Canadian soil has more than enough boron.

Kinsey said that’s correct: many soils have 20 to 200 pounds of boron per acre. However, there’s a huge difference between available and unavailable boron in the soil.

“If you’re looking at the total amount of boron in the soil, basically all the soils in the world have enough boron,” he said.

“But if you’re looking at how much of that boron is in the form that the plant can take and use, almost every soil in the world has a deficiency of boron.”

Kinsey said most plants need .8 to 1.5 parts per million available boron, based on his testing methods.

Levels below .8 p.p.m. are low or deficient.

“Every crop we work with needs 1.5 parts per million boron … if you want to get the best response.”

Plants absorb boron when it’s in the form of borate, but borate leaches out of the soil as quickly as nitrates, Kinsey said.

Therefore, it’s difficult to retain a sufficient amount of boron in lighter soil.

“Most sandy soils … we have to put (boron) on every year to keep it above the minimum,” he said.

“On some heavy soils, we can sometimes skip a year or two, or maybe three.”

Kinsey said boron is critical for seed development because the micronutrient takes starch out of the leaf and moves it into the grain.

Late in the growing season is an opportune time to diagnose boron deficiency. The kernels of a small grain crop such as wheat tell a story about boron because kernels on the middle of the head fill out first, followed by the top and then the bottom, Kinsey said.

“If you’ve got shrivelled grain at the bottom of your wheat head, you don’t have enough boron.”

Kinsey is convinced that western Canadian growers are leaving yield on the table if they don’t have sufficient available boron, but research doesn’t support his argument.

The Canola Council of Canada looked at the potential benefits of boron as part of its Ultimate Canola Challenge program.

Council agronomist Nicole Philp said in a report that canola has higher boron requirements than wheat or barley.

However, three years of applying boron in small plot trials across the Prairies didn’t show a yield benefit. As well, a field scale trial showed no significant yield benefit from boron, regardless of soil pH or organic matter levels.

One site had soil boron levels of .2 p.p.m., but there was still no yield response to added boron.

“Of any research (on boron) that has been done by government groups or independent third parties, we’ve never been able to see a consistent yield response, or protein or oil quality improvement,” Philp said in 2015.

Alberta Agriculture, on its website, says cereal crops do not respond to added boron. As well, too much boron can hamper yields.

“Canola, pea and bean yields have declined by 10 to 20 per cent due to boron toxicity after a two lb. per acre application of boron.”

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