Soil collected in ditches over the winter of 2020/2021 - Credit: County of Newell

By Kristi Cox (intro by Dori Modney)

SOIL EROSION - (3 OF 5)

Soil erosion – Dollars blowing in the wind

Sep 3, 2021 | 1:22 PM

LETHBRIDGE, AB. — As farmers continue the harvest across the prairies, the greatly reduced grain they’re hauling is not the only issue they have or will be dealing with.

The summer’s intense heat and drought will also impact soil erosion, which has become an increasing problem in different areas of the prairie. Last winter, soils were left bare and didn’t freeze under limited snow cover.The result was soil being taken away by prevailing wind that wouldn’t ease up.

With that in mind, four Southern Alberta municipalities, Newell County, the MD of Taber, the County of 40 Mile and Lethbridge County, banded together to shed light on soil erosion.

We have the third of five articles from Farming Smarter , to raise awareness of soil erosion and how it can be mitigated. The latest article, from Kristi Cox, looks at the science behind what is lost in eroded soil…and the cost behind it. —

There’s more to blowing soil than what (painfully) meets the eye. Those airborne particles can hold vital nutrients and even crop disease.

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Finer soil particles such as silt, clay, and organic matter tend to be more vulnerable to wind erosion. They are also generally rich in nutrients and essential for healthy, fertile soil. Gurbir Dhillon Ph.D., research scientist with Farming Smarter in Lethbridge, explained that this is one of the biggest issues with wind erosion.

What else is blowing away with eroded soil? Money!

Dhillon explained that if an inch of soil is lost to wind erosion, approximately 550 pounds of nitrogen per acre will be lost in addition to other major crop nutrients like phosphorus and potassium. Producers must replace them to maintain productivity on their land. The value for these nutrients in terms of equivalent fertilizer costs can be as high as $325 per acre. With several dust storms, the erodible portions of fields can lose this amount of soil in about a decade. This estimate only addresses the loss of macronutrients and doesn’t account for other factors that can reduce profits such as yield decreases, loss of soil structure, less water retention by soils etc.

All this macronutrient-rich soil is going somewhere.

“Some is deposited on roads and in ditches, where it isn’t productive at all,” said Dhillon.

“The deposition of nutrient-rich windblown soils in the drainage ditches or irrigation canals may have other implications such as aquatic weed and algal growth and reduction in water quality.”

To make it worse, the soil can also come with problems like weed seeds or diseases. This is a gift the neighbour doesn’t want.

Clubroot is a soil borne disease that can cause premature death of the plants it affects, including canola. While soil transfer from field to field on equipment is a major cause of spread, wind can also contribute.

Wind soil erosion occurs both close to the ground and up in the air.

“Large soil particles and occasionally even small stones roll and bounce across the surface,” said. Bruce Gossen, research scientist in plant pathology with Agriculture and Agri-food Canada.

Soil collects wherever something blocks its path – Credit: County of Newell

“You find soil moved by strong winds accumulating where the wind velocity drops. There can be 10’s of millions of (clubroot) spores per gram of surface soil from clubroot infested patches in fields. It accumulates in the next field, and that field is then also infested with clubroot.”

Smaller, lighter particles can be picked up into the air and carried long distances.

“Spores are small enough that they can be picked up into the air column and carried across the prairies,” said Gossen “That’s when you get really long-distance movement.”

The percentage of plants infected with clubroot in an affected field will vary, but the costs to production are significant.

“Moderate to severe clubroot generally reduces canola yield by about half,” said Gossen.

Clubroot isn’t the only pathogen to spread long distances via wind. Gossen explained that when soybean rust showed up in the Southern U.S. in the early 2000’s, researchers started watching for spores in Canada.

“In Saskatchewan, we found those spores in our spore traps,” Gossen said. “There weren’t a lot, and the spores likely weren’t viable anymore because they’d spent so long in the upper atmosphere. but spores were moving from the southern USA all the way up to Canada.”

And what about weeds? Is their spread with soil erosion significant?

“In terms of weed seeds, even small seeds are a lot bigger than spores of plant pathogens,” said Gossen.

“(They) tend to not move as far as pathogen spores, but certainly they can be moved from field to field.”

The loss of beneficial nutrients and the potential for spread of disease and weeds makes it vital for producers to act on soil erosion.

Prevention is the best plan, but if the air starts to get thick with blowing soil, emergency measures are available. Nobody wants to see their dollar bills flying away in the wind.