Canada Markets

Past La Nina Events and Impact on Prairie Yields

Cliff Jamieson
By  Cliff Jamieson , Canadian Grains Analyst
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This chart points to the deviation from the 20-year trend realized in Canada's spring wheat and canola yields in past years that were influenced by a La Nina event. Past results show a variable response. (DTN graphic by Cliff Jamieson)

In Tuesday's DTN Spring Planting and Weather Update webinar, DTN Senior Ag Meteorologist Bryce Anderson points towards the ongoing influence of the recent La Nina event, which is in decline but is expected to exert a residual effect into the April-to-June period. This is expected to lead to a colder and wetter forecast for spring, resulting in slow planting progress in the U.S. Midwest and Northern Plains.

Similar cooler and wetter conditions are also expected into April on the Canadian Prairies, which could be viewed as mixed news, given the need for precipitation over certain areas of the Prairies. Eastern Canada could face above-normal precipitation and a slower start to planting.

As far as the potential effect that this type of spring may have on yields, Anderson suggests that trendline yields for corn and soybeans remain a possibility, although his personal estimates point to slightly below trend yields. It is the chance of above-trendline yields that seems to be ruled out in years such as this.

In his presentation, Anderson points to past years that resulted in a memorable impact on crops due to the effects of La Nina events, which included 1974, 1988, 2010, 2011 and 2012. The attached chart shows the impact to Canada's spring wheat and canola yields during these years, by calculating the deviation from the respective 20-year trends. As can be seen, the outcome in terms of yield deviation from trend can vary.

In 1974 and 1988, both spring wheat and canola yields ended below trend, led by a reduction in spring wheat. In 2010 and 11, both deviated above trendline yields while in 2012, results were mixed.

Of the years chosen, 1988 showed the largest swing in yields. Spring wheat yields fell by 10.2 bushels/acre to 18.4 bpa while canola yields fell by 5.2 bpa to 20.4 bpa.

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