Soybean prices closed 5.3% higher in Chicago after data showing US plantings below traders' forecasts and a steep fall in inventories eased fears the market might soon be awash with supply.

While farmers intend to plant a record 76.0m acres of soybean this year, up 300,000 acres year on year, the figure fell well short of the 79.2m acres that traders were expecting, according to Reuters.

Meanwhile, soybean stocks were, at 1.3m bushels at the start of this month, 9.3% lower than a year before and down 974m bushels over three months, a drop some traders believe may also be a record.

The fall in stocks was particularly strong in "off-farm" stores – a group including mills, elevators warehouses and processors – whose inventories dropped 23% year-on-year.

'Beans the strongest'

The data helped soybeans lead a charge in agricultural commodity prices in Chicago.

Vic Lespinsasse at GrainAnalyst.com said: "This morning's USDA report was the main reason for the huge rally in beans."

Other commodities were lifted by "largest scale speculative buying", particularly late in the session, with wheat also helped by a decision by funds to buy back some sold positions.

"Funds sold 1,000 wheat [contracts] this morning but bought it all back and more late in the day, sparking a lot of short-covering in wheat which greatly contributed to the late rally in this pit," Mr Lespinsasse said.

May soybeans closed 47.5 cents higher at $9.52 a bushel, with November soybeans up 50 cents at $8.92 bushel.

May corn gained 18.5 cents to $4.04 3/4 a bushel, with May wheat ending 20.25 cents higher at $5.32 3/4 a bushel.

Switch from corn

The USDA attributed the growth in soybean planting in part to farmers switching over from corn, which has higher growing cost. While corn yields more than three times as much as soybeans per acre, it requires greater quantities of nutrients to achieve its potential.

"Tightening soybean supplies and lower input costs than corn have resulted in farmers intending to plant more soybeans area this year," the USDA said.