WASHINGTON - The United States Department of Agriculture (USDA) Wednesday designated 172 additional counties in 15 states as primary natural disaster areas due to damage and losses caused by drought and excessive heat.

A general view of drought-damaged corn stalks in Missouri Valley, Iowa, Aug 13, 2012. US farmers are watching crops wither in the fields under searing heat as concern mounts that livestock producers cannot afford the soaring cost of corn, a staple for feed. [Photo/Agencies]

During the 2012 crop year, USDA had designated 1,792 counties in total as disaster areas, including 1,670 counties hit by drought, said Agricultural Secretary Tom Vilsack in a statement, adding that the designation made them eligible for assistance such as getting low interest emergency loans.

The severe drought disaster sweeping from the US state of California on the west coast to upstate New York on the east coast have caused significant damage to many crops including corn, soybeans, as well as pastures and rangeland, which is threatening the agricultural harvest in the world's largest producer of grains and meat.

On August10, the USDA reduced the estimate for the 2012 US corn crop to 123.4 bushels per acre, down 23.8 bushels from that of 2011.

According to the US Drought Monitor, as of Wednesday, 63 percent of the nation's hay acreage and 73 percent of the cattle acreage are in an area experiencing drought, while about 87 percent of the country's corn-producing farmland are stricken by drought, down from a peak of 89 percent on July 24.

The USDA has taken a host of measures to help crop and livestock producers cope with the adverse impacts of the unprecedented drought. The measures included a plan announced earlier this week by the department to purchase up to 170 million dollars of pork, lamb, chicken and catfish to help relieve pressure on American livestock producers, and a grant of 30 million dollars authorized by the department last month to help rehabilitate farmland and implement emergency water conservation programs.