US corn stockpiles are far larger than thought and a bumper harvest is on the way, the government said, in reports on Thursday that alleviated worries of a global food shortage and sent corn prices tumbling by record amounts. Corn prices went down by a one-two punch from the Agriculture Department\'s annual acreage and quarterly grain stocks reports, which showed ample supplies despite months of fretting over dwindling stockpiles that drove corn prices to record highs in recent weeks. \"American producers stepped up,\" US Agriculture Secretary Tom Vilsack told Reuters Insider, noting that technology has boosted yields and mitigated concerns about tight world grain supplies. Sky-high prices curbed demand, leaving June 1 stockpiles 11 per cent larger than traders had predicted. Article continues below The news could help ease price shocks that have rippled through to the bottom lines of US food makers and contributed to calls to limit commodity market speculation, which many blame for driving prices higher and fanning global inflation. General Mills and other companies that use US crops to make food have blamed high commodity prices for inflating costs and hurting earnings. Food costs have spiralled globally and US corn prices had risen by as much as 25 per cent this year, made worse by spring flooding in the Midwest, stirring concerns over shortages and causing some livestock farmers to switch to other grains. The harvest, however, is two months away. So there is still uncertainty about the toll of rain and flooding on crops, and grain markets remain volatile. Some traders said, USDA was too optimistic — it has North Dakota plantings down by 1 per cent, for example. State officials say 25 per cent may go idle. \"I don\'t know if this piece of news is enough to completely take away the cost pressures,\" said Morningstar analyst Erin Lash. Historic The report caused havoc in trading pits at the Chicago Board of Trade, where corn for July delivery settled 10 per cent lower at $6.29 a bushel— a record decline by value and per centage — and deferred contracts locked down the limit of 30 cents per bushel. The July contract is in its delivery period and trading without limits. With futures halted, traders rushed to the options pit, where panicked trading indicated futures prices could plunge again. \"There is nothing like this on the chart,\" said Rich Feltes, a veteran grain analyst with R.J. O\'Brien, who has watched the market rise and fall for more than 35 years. \"This is historic,\" he said. Before the report, corn prices had already slid 20 per cent from their peak near $8 per bushel reached three weeks ago. There was added drama for algorithmic traders. A technical equipment glitch in USDA\'s guarded lock-up room led to the release of information by Reuters and other wire services two minutes earlier than scheduled, throwing off some computer programs. \"This is scandalous. Paris was the only market open when the USDA [data] was released. We had no warning that the report would be released earlier than scheduled and we want to know why,\" said a dealer at a leading broker in Euronext futures. In London, the International Grains Council raised its forecast for world corn and wheat crops in the year ahead. Red-hot demand from corn exporters, livestock feeders and processors are forecast to consume every bushel grown in 2010 and eat into reserves, but the higher stocks number was a sign that demand has been rationed. US lawmakers are also weighing ending subsidies worth $6 billion a year to ethanol makers, a move that could affect demand since nearly 40 per cent of the US corn crop goes to ethanol production. The USDA said the corn stockpile was 3.67 billion bushels on June 1, and it pegged plantings at 92.28 million acres. With normal weather and yields, a record-large crop could be harvested. Resurvey The USDA said it will resurvey farmers in four northern Plains states that normally produce a third of the US wheat crop. It includes North Dakota No 1 in wheat last year. A large percentage of those states had not yet planted crops as of early June, when the USDA conducted its acreage survey. July wheat was down 9 per cent at $5.84-3/4 a bushel, posting its biggest percentage loss in more than two years, in sympathy with the losses in corn. Wheat stocks were 4 per cent larger than traders expected and plantings were down marginally. The USDA report was mildly supportive for soybeans, with plantings 2 per cent smaller than traders had expected.