Canadian farm officials remained relatively cautious over the country's export potential even as they hiked their estimate for production, thanks to expectations of a record yield.
Canada's farm ministry, AAFC, lifted by 2.4m tonnes to a record 33.2m tonnes its forecast for the domestic wheat harvest, noting that "yields are a new record", as highlighted by an official report two weeks ago.
The ministry noted "extremely good growing conditions, despite late seeding".
However, it raised its forecast for exports by only 650,000 tonnes to 20.5m tonnes, despite acknowledging "growing world demand" highlighted in rapid starts to 2013-14 exports for the European Union and the US.
Supplies of quality wheat from the former Soviet Union have been constrained by poor harvesting conditions, while weather upsets have boosted import demand from the likes of Brazil and China.
Many commentators have urged caution over Canada's infrastructure, with Richard Feltes at broker RJ O'Brien, for instance, saying that "key going forward will be Canada's logistical ability to move these massive crops into export channels".
While Canada has shipped larger volumes of wheat before, with shipments hitting a record 23.5m tonnes in 1986-87, that was before the country was a major exporter of canola too, with volumes of non-farm commodities, such as potash, higher too.
Export hopes are being little helped by the prospect of a strike at Canadian National Railway, the country's top rail operator, after the breakdown of talks between management and union leaders over proposals to force staff to work longer hours with less rest time between trips.
"In the short-term, the increased [wheat] supply from Canada may not be available due to the threat of a strike by Canadian rail workers," Commerzbank noted.
'Booked to capacity'
The Canadian Wheat Board, the former grain export monopoly for Canada's Prairies, responsible for some 90% of national wheat output, said that thanks to the size of the harvest "many grain export companies are booked to capacity for months ahead".
This squeeze was being reflected in the elevators network too, prompting a widening discount of cash prices to futures values.
"One thing that we're seeing is widening basis levels," CWB pool manager Dave Przednowek said.
"Futures prices have been rallying lately for wheat, but most farmers are not seeing that at their elevators.
"Elevators are booked to capacity, and they're widening out their basis levels to discourage deliveries."
AAFC trimmed to Can$230-260 a tonne, down Can$5 a tonne from its mid-September figure, its forecast for the average cash wheat price in 2013-14 despite a rise of 6.0% in Minneapolis spring wheat futures over the period.
The ministry also noted the "wider spreads for grades" in this year's Canadian wheat crop, whose protein levels were coming in "lower than last year and lower than normal".
For canola, AAFC lifted its production forecast by 1.25m tonnes to a record 16.0m tonnes, but saw most of that being reflected in export volumes.
The estimate for canola exports was lifted by 1.1m tonnes to an all-time high of 8.0m tonnes.
"Exports are forecast to rise by 10% on strong world vegetable oil and protein meal demand," ministry oilseeds analyst Chris Beckman said.
However, the ministry lowered too its estimate for average 2013-14 canola prices, to Can$500-540 a tonne from Can$540-580 a tonne.
For barley, the production estimate was raised by 440,000 tonnes to 9.43m tonnes, and the export forecast by 100,000 tonnes to 2.30m tonnes.