WASHINGTON — A record large corn crop in China resulted in a 7-million-tonne increase to 1,284 million tonnes in projected 2012-13 world coarse grain supplies, the U.S. Department of Agriculture said in its Dec. 11 World Agricultural Supply and Demand Estimates and in its latest Feed Outlook.

China’s National Bureau of Statistics pegged its first estimate of 2012-13 corn production at a record 208 million tonnes, which was “adopted” by the U.S.D.A. and was up 8 million tonnes from the U.S.D.A.’s November forecast for China. The U.S.D.A. said “economic information, weather data and satellite imagery support the large increase” in China’s corn output. The 2012-13 corn production estimate is up 8% from China’s outturn of 192.8 million tonnes in 2011-12.

A total world increase in corn production of 9.4 million tonnes from November partially was offset by lower output of barley, oats and grain sorghum, resulting in the net 7-million-tonne coarse grain increase, the U.S.D.A. said.

China reported corn harvested area of a record 34.95 million hectares in 2012-13, up 4% from the previous year. The number of harvested acres planted to corn has been climbing in China for every crop year since 2003-04. Yield has increased every year since 2009-10.

The U.S.D.A. said a number of factors contributed to the record crop, including a favorable price for corn at the time of planting compared to other field crops such as soybeans and cotton. Good growing conditions limited losses in the harvest-to-planted ratio in most areas with warmer-than-normal temperatures and plenty of precipitation aiding the corn crop in key regions of China.

Total coarse grain production in the United States, in contrast, was forecast at a drought-reduced 284.8 million tonnes in 2012-13, unchanged from a month ago and down 12% from 2011-12, the U.S.D.A. said. U.S. corn production was estimated at 272.4 million tonnes in 2012-13, down 13% from a year earlier.