First frost dates pushed

Today’s farmers have a lot more time to grow a crop than those that came before them.

The numbers should provide some comfort to growers in Western Canada, where crops in many regions that aren’t affected by floodwaters are delayed following a cool spring and plenty of rain in the early summer.

“Farmers, I think, are accepting or have adapted to the longer growing season and realized that they have more than the 100 days than they used to have in the 1960s,” said Elaine Wheaton, a climatologist and emeritus researcher with the Saskatchewan Research Council.

Thirty-year averages for first frost dates favour the middle of September for much of Saskatchewan, but growers may have noticed recent fall frosts pushed further into the month and even later in some cases.

The frost-free season experienced in central Saskatchewan has grown by almost a month since the 1960s, said Wheaton. Researchers peg the growth at five days every 10 years over that period and draw a link to climate change caused by increases in greenhouse gases.

That’s at least 25 days over a 50 year period and areas farther south can see even more.

In 2012, some growers saw a spring to fall frost-free season extend to 160 days. Wheaton said growers can expect to see extremes, whether they be hot or cold, short or long.

“The big thing is that there is a tremendous variability from year to year of the frost-free season, either spring or fall … and a great variability over the landscape too from one field to the other,” said Wheaton, “but there is a very strong pattern of increasing length of the growing season.”

Longer growing seasons are noted elsewhere on the Prairies with increasing crop heat units assisting the introduction of new crop types like soybeans and corn. Alberta and Manitoba both see first frost averages pushing into the third week of September.

The check wheat variety, AC Barrie, has a relative maturity of 100 days, according to the latest Varieties of Grain Crops publication, making June 10 the seeding deadline for crop insurance in Saskatchewan. Depending on conditions, that deadline sees the crop maturing around Sept. 18.

Canola maturity dates stretch from 92 in some regions to more than 125 days. Many pulse crops carry an early to medium maturity rating, although soybean varieties exceed 120 days by the book. Some growers have seen better results, but a late spring in 2014 may have led producers to reconsider testing the crop as plants must approach maturity before the first fall frost to be insurable.

“In 10 years, we’ll have a much longer growing season than even now,” said Wheaton. “My question is: are plant breeders taking advantage of this information and this very strong trend? It’s not going to go away.”

The Saskatoon region saw its last freezing event on May 14, according to Environment Canada, although weather conditions delayed seeding operations at the start of June. Ninety-five percent of crops were seeded in the middle of June, according to the Saskatchewan agriculture ministry, which put progress behind most of Alberta and slightly ahead of Manitoba.

Subsequent rain and flood events, however, have left a significant number of crops in parts of eastern Saskatchewan and Manitoba unsalvageable. Saskatchewan’s most recent crop report estimated the damage at two to three million acres. Delayed crop development was already noted across the Prairies.

Drew Lerner of World Weather Inc. said it’s too early to provide a frost forecast for the Prairies. He’s keeping his eye on a handful of cool surges over the next few weeks, which could make growers looking to dry out saturated crops nervous.

“What the trend models are telling me is that as we get into the end of August and September those cold surges that we’re going to have this month and mid-August should become much less significant,” he said last week.

Lerner has a conservative stance when it comes to the lengthening growing season.

“The last few years we’ve benefited greatly from these later frost and freeze events, but I do not believe that we’re going to see that continuing for much longer,” he said. “(Warm air system) El Nino will possibly help us go another year, but I really think there’s going to be a little bit of support for a quick shot of normal frost-freeze conditions.”

Climate projections show Western Canada may experience fewer negative impacts of climate change than other parts of the world. But while crop yields may get a boost in the short term, a longer growing season is expected to come with greater challenges from pests and diseases. Researchers have also predicted more extreme and unpredictable weather events, including flooding and a serious threat from heat shocks.

Saskatchewan has already seen an increase in the average number of days exceeding 35 C, which have shifted from one to three per year in the 1960s to two to five in the 2000s, according to SRC data.

“For the future, we see more intense and probably larger areas of drought and probably further north drought,” said Wheaton.

One project at the Semiarid Prairie Agricultural Research Centre in Swift Current, Sask., used weather records and climate models to determine that seeding dates in southwestern Saskatchewan may advance by as much as seven to 11 days in the coming decades. That puts growers in southwestern Saskatchewan in the fields as early as April 5-9, with crops maturing much earlier.

A survey of research papers reveals similar modelling work is being conducted with other crops, everything from hay to canola.

The Prairie Adaptation Research Collaborative said early spring seeding will also improve pulse production in semiarid regions. On its website, PARC applauds the use of zero-till and conservation management practices for reduced runoff, erosion and fuel and fertilizer consumption, but says further advances will be required, like tall stubble systems.

“I think producers are making innovations every year. I think that the example of minimal tillage is an amazing innovation. Matching fertilizer more to what the crop requires. Watching these temperatures like they did this year and, as it gets later and later, they say we need a different crop,” said Wheaton.

“… I think there are many examples of innovation, but we might have to ramp that up quite a bit.”

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