WASHINGTON — With the nation’s worst drought in a half-century continuing to decimate crops, the government on Friday slashed its estimate of the soybean yield, made only a month ago, to the lowest level since 2003 and its estimate of the corn yield to the lowest level since 1995.

The smaller harvests will drive up prices for food and animal feed, analysts said. The prospects are also increasing pressure on the Obama administration to divert less corn to the production of the biofuel ethanol.

Agriculture Secretary Thomas J. Vilsack, visiting drought-stricken farmers in Nebraska on Friday, said that despite the reduced crop production, farmers are in better shape today than during the last major drought, in 1988.

“Last time only 25 percent of farmers had crop insurance, but this time over 85 percent are covered,” Mr. Vilsack said, noting that the government was still forecasting the eighth-biggest corn harvest ever.