OQUAWKA, Ill. (AP) _ Once he coaxed tall, sturdy corn stalks from rich, black Mississippi River bottomland. Now Howard Pruett bulldozes mountains of dirty sand from fertile farmland that looks like a moonscape.

Flooding last year deposited a half-dozen piles of river silt that stretch 200 yards each and rise 20 feet high. Debris in the treetops is a reminder of the Mississippi's power.

Instead of simply planting seeds, hundreds of Midwest farmers will spend the spring like Pruett, patching levees, scraping sand, filling holes and plowing silt into the ground.

The disaster of '93 lingers. And the threat of more flooding from melting ice and recent rain looms.

''We had thought about retiring,'' Pruett, 69, said. ''But we couldn't walk away from a mess like this.''

Even if the mess is removed, what remains? The flood's damage below the surface is unknown. Experts wonder if soil that often produced 200 bushels of corn per acre has the stamina to produce hearty stalks again.

Earthworms, soil creatures and micro-organisms, all crucial to soil chemistry, ''don't normally thrive in an environment saturated for months on end,'' scientist Bob McLeese of the U.S. Soil Conservation Service said.

''It may take a while for the ecosystem to bounce back,'' he said. ''What will that do to crop yields? Nobody really knows.''

Nearly 900,000 acres of Illinois' 20 million of corn and soybeans production were lost to the flooding caused by last summer's heavy rain, primarily along the Mississippi and Illinois rivers, said Chet Boruff, deputy director of the state Agriculture Department. The crops either couldn't be harvested or planted.

The federal government estimated losses at $610 million in Illinois, which normally leads the nation in soybean production.

The situation was worse in Iowa, where 6.5 million acres, or about a third of the state's cropland, were flood damaged. Crop losses were estimated at more than $2 billion. Iowa is the nation's leading corn producer, but slipped to second place behind Illinois in 1993 because of the flood.

In Missouri, 500,000 acres of farmland suffered heavy sand deposits or were at risk to renewed spring flooding because levees were unrepaired. Crop losses were estimated at $500 million as the corn harvest fell 50 percent behind 1992 levels.

In Minnesota, about 1.7 million acres of corn, or 27 percent of the crop, were lost to flooding, along with about 900,000 acres of soybeans, or 15 percent of the crop.

In Kansas, about 25 percent of the state's 20.3 million acres of cropland were idled due to flooding and weather-related problems, such as hail.

The United States Department of Agriculture said $1.06 billion has been paid to 318,079 farmers in nine states who couldn't plant or lost their crops in 1993.

Even as some farmers are getting disaster payments, thick ice remains on their fields.

Claire Wilson of Hillview said 4,500 acres in west-central Illinois remain under Illinois River water, including his farm. Planting is a distant dream until the ice melts and they can resume pumping.

Then they will face mud that makes plowing impossible. Tractors will have trouble crossing the fields, much less pulling plows through the muck.

''People think the flood is over, but it's a long way from being over here,'' Wilson said.

The water has receded from Bud Pieper's 3,000-acre farm in Wever, Iowa, but he and his sons are still working the ground, rebuilding their homes and trying to repair 15 large buildings where they breed 1,300 sows.

''The figures tell you it will take five years to recover from this,'' Pieper, who had no flood insurance, said.

Pruett, a Henderson County farmer, plans to push aside as much sand as possible and plant around the huge mounds. He will dip into his savings to pay for this year's crop.

''They're going to farm come hell or high water, literally,'' McLeese said of farmers like Pruett. ''It's in their blood. It's their livelihood. They don't feel like they have a choice.''