Informa's downward adjustment in corn and soy production levels is based on the assumption that August will continue the stressful weather experienced thus far in the 2012 growing season.

The data were released as a special update on US corn and soy assuming unfavourable August weather. Informa will release its normal August production report based on surveys on August 3.

Informa lowered its estimate for the US corn harvest to 11.475 billion bushels from its early-July estimate of 12.49 billion bushels, traders said. The firm cut its yield estimate for the crop to 134 bushels an acre from its previous estimate of 142.5 bushels an acre, they said.

"The stressful weather pattern the US is experiencing has been reducing crop prospects on a daily basis," Informa said in the report.

Grain users are uncertain about the size of the upcoming autumn harvests after intense heat stressed the crops. Farmers need to harvest a big corn crop to replenish low inventories.

Informa lowered its estimate for the soy harvest to 2.890 billion bushels from 3.012 billion bushels, traders said. It pegged the average yield at 38.5 bushels an acre, compared to its early-July estimate of 40 bushels per acre.

By contrast, the USDA in July estimated the US corn crop at 12.970 billion bushels, using a 146 bushel-an-acre yield, and soy output at 3.050 billion, using a 40.5 bushel-an-acre yield. The USDA is scheduled to release updated figures August 10.