* Exports up 13 pct in January from December
* Inventories 29 pct above 5-year average
WINNIPEG, Manitoba, Feb 14 (Reuters) - Exports by North American potash producers jumped in January, after their marketing organization Canpotex Ltd signed a supply contract with Chinese buyers, according to the world's top producer of the crop nutrient, Potash Corp.
Potash supplies piled up last year as key global consumers China and India delayed signing new supply contracts with Canpotex, the offshore marketing company owned by Potash Corp, Agrium Inc and Mosaic Co. Canpotex announced a six-month contract with China on Dec. 31, and a deal with India followed on Feb. 7.
Potash exports by the North American producers jumped 13 percent in January from the previous month to 657,000 tonnes and were 38 percent above the pace set a year earlier, according to data posted on Potash Corp's website on Thursday.
Domestic sales, mainly to the United States, were up 3 percent from the previous month and 67 percent above the year ago pace at 477,000 tonnes.
Inventories at the producer level eased 1.3 percent or 39,854 tonnes in January to 3.117 million tonnes, but are 29 percent larger than the previous five-year average.
The vast majority of the potash produced in North America is mined in the Western Canadian province of Saskatchewan, where Potash Corp has its headquarters.