Corn futures plunged the exchange limit in Chicago, with soybean and wheat prices falling too, after the US said that its stocks of all three crops were larger than had been thought, easing concerns over tight supplies.
The US Department of Agriculture added to ideas of an easing in the corn supply squeeze by pegging domestic sowings of the grain at 97.3m acres, a little above market expectations, and the largest area since 1936.
The USDA said that US corn inventories as of the beginning of the month had fallen to 5.40bn bushels, down some 600m bushels year on year, but well above the figure that investors had expected following last year's drought-hit harvest.
Corn futures for May locked down the exchange limit of $0.40 a bushel, or 5.4%, at $6.95 ¼ a bushel after the data.
The new crop December contract dropped 5.7% to $5.38 ½ a bushel, a nine-month closing low.
For wheat, the USDA said that start-of-month inventories were, at 1.23bn bushels, a little higher than a year before, rather than showing the small decline that investors had expected, spurred by ideas of livestock feeders switching grains.
Wheat prices have been relatively weak compared with those of corn, losing their typical premium at time, although this dynamic only appeared for a limited time before March 1.
Plantings of the grain for the 2013 harvest were pegged at 56.44m acres, including larger sowings of winter wheat and spring wheat than had been expected, offset in part by a surprise tumble in durum seedings.
Wheat futures for May tumbled 6.7% to $6.87 ¾ a bushel in Chicago, the third lowest finish for a spot contract in nine months.
US soybean inventories too were higher than expected, at 999m bushels, albeit well below the 1.37bn bushels a year before, reduced by a particularly strong demand.
March 1 US crop stocks, change on year and (on market forecast)
Corn: 5.399bn bushels, -10.4%, (+386m bushels)
Soybeans: 999m bushels, -27%, (+64m bushels)
Wheat: 1.234bn bushels, +2.9%, (+57m bushels)
However, the data gave investors one crumb of comfort in showing that farmers intend to sow 77.13m acres with the oilseed this year, significantly below expectations and, indeed, a little below the 2012 figure.
Investors had expected farmers to turn more to the crop, given a relatively strong performance by soybean futures in February, the month in which insurance payout rates are determined, which appeared to have boosted their appeal compared with corn.
Soybean futures for May closed down 3.4% at $14.04 ¾ a bushel.
However, feeder cattle futures bucked the negative trend, soaring the exchange limit of 3.0 cents to 143.40 cents a pound in New York for April delivery, on hopes that extra grain supplies would lower prices, and improve appetite for rebuilding herds on feedlots and ranches.
Prospective crop plantings, change on year and (on market forecast)
Corn: 97.282m acres, +0.1%, (+30,000 acres)
Soybeans: 77.126m acres, -0.1%, (-1.27m acres)
All wheat: 56.44m acres, +1.3%, (in line)
Includes winter wheat: 41.988m acres, +1.6%, (+172,000 acres)
and spring wheat: 12.701m acres, +3.4%, +442,000 acres
and durum wheat: 1.751m acres, -17.5%, -366,000 acres
In New York, cotton futures for May showed gains of more than 1% at one point, before closing down 0.1% to 87.37 cents a pound
The USDA poured doubt on expectations that a rise of some 20% in prices this year would tempt farmers to curtail plans for slashing sowings of the fibre.
Cotton sowings were pegged at 10.03m acres, some 1.0m acres above an industry forecast last month.
But the figure was still well below figures approaching 10.5m acres which have been circulating in the market in the last week, and 19% down on year-ago plantings.
Farmer comments suggest that "planted area in Arkansas, Louisiana, Mississippi, New Mexico, and Oklahoma will all be record lows", the USDA said.
The USDA said that its forecast for corn sowings reflected ideas of "record-high acreage in Arizona, Idaho, Minnesota, Nevada, North Dakota, and Oregon", offset by declines in most states in the Corn Belt, "which experienced severe drought in 2012".
Indeed, farmers in the eastern Corn Belt especially look set to turn increasingly to soybeans, which proved relatively resistant to last year's drought.
For spring wheat, "the largest expected acreage increase from the previous year is in North Dakota", the USDA said, while durum plantings are "expected to be down in all states except South Dakota," and at a record low in Idaho.