Spring flooding in the northern Plains and western Corn Belt will have a marginal impact on corn and soybean plantings, according to a USDA survey of growers and initial tallies of flooded land. With normal weather and yields, there would be limited impact on production of the two most widely grown U.S. crops, thanks to the huge amount of cropland nationwide.Farmers intend to plant a combined 177 million acres of corn and soybeans this spring, said USDA in its annual Prospective Plantings report on Friday. By comparison, estimates of farmland flooding range from 500,000 acres in Iowa and western Nebraska to 1.1 million acres in the Midwest.If farmers follow through on plans to plant 92.8 million acres of corn and 84.6 million acres of soybeans, they would be on track to harvest the second-largest corn crop and the fourth-largest soybean crop on record after allowing for abandonment of some of the land due to bad weather, disease or pests. USDA projects 1 million acres, on average, would produce 176 million bushels of corn or 49.5 million bushels of corn this year.The USDA report was based on a survey of more than 82,000 farmers during the first two weeks of March, just before a blizzard swept cattle-producing western Nebraska and heavy spring rains accelerated snowmelt in the upper Missouri River basin. The spring planting season is on the horizon and there is widespread concern if flooding will persist and whether fields will dry out in time to produce a crop.