U.S. corn futures climbed Wednesday, driven by worry that the poor spring weather will reduce acreage and yield prospects in the eastern Midwest.

Grain users are nervous about the size of the 2011 crop and fear farmers won't plant as many acres as they intended due to soggy fields in the eastern corn belt. Farmers need to harvest a big crop to replenish inventories, which are projected to fall to a 15-year low this year due to strong demand.

The uncertainty of corn seedings is a focal point in the market, adding to an already supportive theme of tight supplies, said John Kleist, senior grains analyst with ebottrading.com.

U.S. Department of Agriculture's weekly crop progress report, issued Tuesday, had already raised red flags of how much corn will be planted. The government said 86% of the crop was in the ground, below the past average of 95%.

Grain users are forced to raise prices to secure grain amid the potential for less available supplies from eastern corn-belt areas. The combination of farmers remaining reluctant sellers of grain, reasonable export demand and a strong draw from such domestic users as ethanol plants and food processors is expected to keep supplies tight throughout the summer, Kleist said.

The market retraced Tuesday's losses, as traders added risk premium back into prices with the uncertainties of 2011 production generating enough independent strength to offset spillover weakness from stumbling wheat futures, Kleist added.

The Linn Group, a brokerage firm, pegged corn plantings at 87.2 million acres, down 2.5% from its May estimate and 5.4% from USDA's March estimate. The forecast indicates inventories would become extremely tight, assuming normal yields.

Nevertheless, despite the gains in prices, futures remained within a recent trading range, with improved planting outlooks this week limiting advances.

CBOT July corn jumped 11 cents, or 1.5%, to $7.58 1/2 a bushel

U.S. wheat futures finished sharply lower for the second consecutive day on projections that global supplies will rise as Russia ends its export ban July 1. Rains in Western Europe added pressure as they ease concerns about crop losses due to drought, analysts said. CBOT July wheat dropped 2.9% to $7.59 1/4 a bushel; KCBT July lost 1.8% to $8.91 1/2; and MGEX July dropped 1.9% to $10.05 1/2.

U.S. soybean futures climbed, with prices jumping amid uncertainty of acreage in the face of tight supplies. CBOT July soy ended up 0.7% at $13.86 1/4/bushel.

Other Markets

CBOT July soyoil settled down 0.1% at 58.43 cents/pound, and July soymeal ended up 1.5% at $360.70/short ton. U.S. rice futures close down the daily 50-cent limit on spillover pressure from steep losses in the wheat market. Improvements in U.S. rice planting and condition ratings add pressure. CBOT July rice fell 3.3% to $14.56 per hundredweight. The daily limit expands to 75c Thursday.

Ethanol futures finish higher, following an increase in corn prices. Ethanol for July delivery gains 0.5 cent, or 0.2%, to $2.65 per gallon. Oat futures pull back on profit taking, with the July contract slipping 3 cents, or 0.8%, to $3.83 a bushel.