Soybean futures rose by 2% in the United States on Thursday after the US Department of Agriculture reported export sales that were larger than expected.
Corn and wheat also climbed on markets at the Chicago Board of Trade.
China has ordered more than 1 million tonnes of soybeans: 283,500 tonnes for delivery before the start of the 2009 harvest, and 830,000 tonnes for shipment after 1 September.
The department is forecasting US farmers will sell 27.5 million tonnes of soybeans in 2008/09 - a quarter of the world's soybean trade.
The Commerce Ministry in China on Thursday issued a revised soy import estimate for July: 4.28 million tonnes compared to its previous forecast of 3.56 million.
US corn and wheat exports last week were also bigger than many expected.