The Soviet Union canceled another wheat order.

The order was for 150,000 metric tons of U.S. wheat--about 5.5 million bushels--that was supposed to have been delivered through Sept. 30, the Agriculture Department said. Moscow has periodically canceled grain orders, presumably because of shipping and other scheduling problems at Soviet ports, department officials have said. Despite the cancellation, grain bought for delivery in 1984-85 under a long-term supply agreement now totals a near-record 15.2 million tons, including 12.2 million tons of corn and 2.96 million tons of wheat. A metric ton is about 2,205 pounds.