High crop prices and favorable weather are triggering bigger harvests world-wide, but grocery shoppers probably won't see much relief anytime soon.

The U.S. Agriculture Department Tuesday predicted that the world's farmers will produce record amounts of wheat and oilseeds this year. Based on Aug. 1 conditions, U.S. farmers are expected to harvest 12.3 billion bushels of corn, which would be their second-largest crop ever, trailing only last year's 13.1 billion-bushel harvest.

But global demand for grain is rising so quickly that even bumper harvests can't puncture the two-year-old grain-price rally that has been inflating retail food prices. USDA economists expect the season average price of the new corn crop, which will be harvested in a few months, to hover around $5.40 a bushel, give or take 50 cents.

While corn-futures prices have cooled from the $7 level that was hit in June -- when flooding sparked fears of widespread crop damage -- the USDA price forecast means that food executives and livestock producers can expect to pay twice as much for corn in the foreseeable future as they did for much of the previous decade.

"Crop prices are settling at a new and higher plateau," said Dan Basse, president of AgResource Co., a Chicago commodity-forecasting firm.