Corn dropped to a one-month trough, pressured by larger-than-expected US and global ending stocks estimates for the grain, while wheat declined despite a surprise fall in stock forecasts.

Chicago Board of Trade March soybeans had declined 1.1 percent to $14.36-1/2 a bushel by 0358 GMT. That was just above their session trough of $14.32-1/2 a bushel - the lowest level since January 25. They lost 2.3 percent in the previous session.

"We are seeing some follow-through selling in beans and corn after the USDA crop report," said Luke Mathews, commodities strategist at the Commonwealth Bank of Australia.

March corn dropped 0.46 percent to $7.05-3/4 a bushel, having hit a session low of $7.05-1/2 a bushel, the lowest since January 11. Corn closed down 0.24 percent the session before.

The USDA cut its US soybean end-of-season stocks forecast to 125 million bushels, from 135 million a month ago, but raised its global ending stocks view 1.1 percent to 60.12 million tonnes after a million-tonne drop in Argentina's crop was offset by a million-tonne gain in Brazil.

Traders are continuing to focus on South American weather forecasts.

Rains forecast for dry areas of Argentina may help stem recent corn and soybean yield losses. Drier conditions will be needed in Brazil, where rains have stalled some early harvest activity and threatened to delay export loadings.

The corn market also faced pressure as the government raised its outlook for US and global ending stocks by more than expected as high prices blunted demand for the grain.

Wheat fell in line with corn, despite an unexpected cut to projected US wheat carry-out in the USDA report.

March wheat dropped 0.23 percent to $7.53-1/2 a bushel, having closed up slightly the session before.

The USDA said the stockpile of US wheat at the end of the marketing year on May 31 will shrink to 691 million bushels, down from its previous forecast for 716 million bushels and the smallest in four years.