Promising alternatives highlighted in U of M study of cropping systems

Winnipeg Free Press

a day ago

Opinion
The 2021 drought was one of the worst in Prairies history, but it was serendipitous in one way.
It coincided with University of Manitoba research designed to better understand how different cropping systems perform under warmer and drier conditions, which many scientists predict will be our future.
A dry 2020 growing season, followed by winter precipitation that was one-third of normal set the stage for the yield-crippling event of 2021. Manitoba crop yields plummeted by a range of 22 to 37 per cent and by as much as 70 per cent in some municipalities, according to a provincial government report.
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The U of M research suggests the crops and farming practices of today will become less profitable under such scenarios. But it also found some promising alternatives.
While farmers look to the amount of rain and the available soil moisture as key determinants of yields, researchers are increasingly focused on the role of atmospheric dryness, which is the air's ability to soak up more moisture as temperatures rise.
Research I cited last week cited blames 'atmospheric evaporative demand' for increasing the intensity of drought globally by more than 40 per cent over the past four decades.
The Manitoba study considered a similar metric: 'vapour pressure deficit,' which is also proving to be an important indicator of drought stress. That deficit during this two-year study was well above the long-term average.
'The main objective of this study was to compare cropping systems that incorporated … diversity, intercropping, cover cropping and heat tolerance with a 'business-as-usual' rotation,' the research team consisting of S.K. Curtis, M.H. Entz, K.A. Stanley, D.J. Cattani and K.D. Schneider reports in the Canadian Journal of Plant Science.
The research team tested a range of cropping systems, including one typical for this region: wheat-canola-wheat-soybean.
They also looked at a warm-season blend of crops, which some believe will expand in acreage under a rising temperature scenario. That included corn-sunflowers-dry beans-canola.
Another system focused on increasing biodiversity by growing nine crops in a combination that included intercropping (growing two annual crops in the same field), cover crops (crops sown after the annual crops are harvested) and a green-fallow crop to provide nutrients. This system increased the breadth of crops grown and the length of growing time as well as producing much of its own nitrogen, which reduces cost and risk.
There was also a trial featuring Kernza, a type of perennial wheat that can be harvested annually for grain, and an organic rotation.
The business-as-usual cropping system yielded 71 per cent of the biodiverse plots and only 59 per cent of the warm-season system. Economically, the net returns from the business-as-usual and the biodiverse scenarios were about the same, except the biodiverse system used 50 per cent less nitrogen fertilizer, one of the greenhouse gas emissions culprits.
The warm-season blend of crops performed the best economically, but its production was less stable than the biodiverse rotation due to herbicide-resistant weeds.
In addition to yield and economics, the researchers measured water use efficiency, yield stability and the number of days the soil contained 'living roots,' which is a measure of soil health.
'The biodiverse rotation represents an agroecological approach to crop production with the highest levels of diversity and stability,' the paper says. But even though that system gave equivalent returns economically, it's harder to do, requiring more time, equipment and knowledge. Those barriers are hard to overcome.
Surveys show farm planting decisions are driven by the potential for yield and economic returns, more than a focus on stability. There's a reason why they call farming a gamble.
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That implies the go-to adaptation strategy for many will be to incorporate more warm-season crops into farming systems, even though there could be higher degrees of yield variability.
So why should consumers care?
Thinking back to the 2021 drought, although farmers suffered significant yield losses, the economic pain was muted by higher commodity prices for the crop they harvested and government compensation.
However, those production shortfalls were a contributing factor to food price inflation of more than 10 per cent in the years that followed.
Laura Rance is executive editor, production content lead for Glacier FarmMedia. She can be reached at [e-mail]
Laura RanceColumnist
Laura Rance is editorial director at Farm Business Communications.
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