A Taiwan importers' association bought soybeans Tuesday, in what might seem a routine tender. But it wasn't.

Instead of buying its normal one cargo of around 60,000 metric tons, the Taichung-branch of Taiwan's Breakfast Soybean Procurement Association bought three, including one not due for shipping until next July, and it was the second time in less than a week that Taiwanese buyers had taken above-average or far-forward amounts.

This locking-in of supplies replicates moves by soybean importers elsewhere who, faced with record high prices, are increasingly worried about what happens next: they are already in uncharted pricing territory and a future fall in supplies seem all-but-inevitable.

It also coincides with soaring wheat and corn prices as dry weather in Latin and North America, Russia and Australia, among others, eat into harvests.

The time-bomb ticking under the global soybean trade is potentially more explosive than in other crops.

Unlike, corn and wheat which are direct substitutes for each other, replacements for soymeal extracted from beans are limited, and even costlier. Soymeal obtained after crushing beans is high in protein value and used in animal feed.

Worries about soybean supplies started with drought in several parts of South America earlier this year, but at the time there were hopes that the shortfall would be made up by a good crop in the U.S., which hasn't happened, said Abdolreza Abbassian, Rome-based secretary of the Food and Agriculture Organization's Intergovernmental Group on Foodgrains.

The combination of two back-to-back droughts has made supply even tighter, Mr. Abbassian said.

The U.S., the world's top soybean producer and exporter, may almost run out of soybeans by the time the next round of plantings are harvested in September 2013, as the current crop is wilting in the fields due to lack of rain.

"Technically the soybeans inventories may not fall to absolute zero because there are always at least some soybeans somewhere, but still by the time the 2013 harvest arrives a year from now the trade pipeline will be empty and the U.S. will be importing more soybeans than usual," Roy Bardole, chairman of the U.S. Soybean Export Council said.

More than 93% of the global soybean trade is controlled by the U.S. and South American countries.

This year's U.S. crop is being snapped up fast, with about 55% already sold for export, a record for this time of the year. By the time the harvest is over, the entire crop is expected to be have been sold for forward shipments, said Karl Setzer an Iowa-based analyst with MaxYield Cooperative.

Rather than buying less due to reduced availability and higher prices, importers are stepping up purchases as a hedge against future rise in prices.

Last week, the London-based International Grains Council cut its forecast for global soybeans, corn and wheat output in 2012-13 by 3.8 million tons, 26 million tons and 3.0 million tons respectively.