* Saskatchewan May rainfall twice the normal amount
* Overall Saskatchewan planting ahead of average
* Eastern Alberta wet, seeding falling behind
By Rod Nickel
WINNIPEG, Manitoba, May 30 (Reuters) - Steady rains have delayed planting in the canola belt of Saskatchewan, raising the chances of some Canadian farmers switching to shorter-season crops or fields going unplanted.
Most growing areas in Saskatchewan, which grows more canola than any other Canadian province, received more than twice as much precipitation as normal in May, according to the Canadian government's Drought Watch website.
The rain is welcome in western Saskatchewan, but in the east-central part of the province -- home to three major canola crushing plants -- planting is lagging behind, said Grant McLean, a cropping management specialist for the provincial government.
"There's water running in the fields," he said. "The rain has slowed things down."
Overall in Saskatchewan, crop planting is about three-quarters complete, ahead of the normal pace, McLean said.
Alberta planting has lagged this spring, while Manitoba seeding is nearly complete.
Canada is the biggest grower of canola and the top exporter of spring wheat, durum and oats.
Farmers in eastern and central Saskatchewan typically grow plenty of canola to supply oilseed crushing plants owned by Cargill Ltd, Richardson International Limited, and one co-owned by Louis Dreyfus Corp and Mitsui & Co Ltd.
Farmers in those areas are considering switching some acres from canola to shorter-season oats or barley to avoid autumn frosts, McLean said, but they will be hesitant to do so given canola's greater profitability.
As the rains fell in the past week, ICE Canada November canola futures rose 2.2 percent.
As of May 21, overall crop planting in east-central Saskatchewan was less than half finished.
The wet conditions raise the prospect of more land going unplanted, McLean said, but farmers still have nearly three weeks until June 20, Saskatchewan's crop insurance deadline for farmers to qualify for yield-loss liability.
Western Canada planting conditions have generally been much better than the past two years, when severe spring flooding washed out large stretches of farmland.
Statistics Canada forecast in April that western farmers would leave nearly 4 million acres unplanted this year, less than one-third of the previous year's fallow land.
But after warm, dry conditions in early spring, rains fell in abundance in May, accompanied by a series of light frosts that caused some minor crop damage.
In Alberta, Canada's second-largest producer of wheat and canola, previously dry eastern areas received more precipitation than normal in May, stalling planting progress.
"There are some significant chunks of land unseeded and people are getting back onto their land (after) almost a week delay," said John Mayko, who farms east of Edmonton and is an agronomist with Agri-Trend. "There are fields with as much water standing on them as they did when the snow melted in spring."
Overall seeding in Alberta was just over half finished as of May 17, well behind the usual pace, according to the provincial government.
Environment Canada is forecasting rain in parts of Saskatchewan on Wednesday and Thursday and possibly during the weekend. Alberta's five-day outlook is mostly dry.
Southwestern areas of Manitoba, where seeding lags the rest of the province, looks dry, with a small chance of rain on Thursday.
"If we get a string of dry weather, we can still get almost all of the acres planted," said Chuck Penner, an analyst at LeftField Commodity Research.