After watching crops shrivel in the summer and harvests shrink in the fall, farmers have another drought worry before next spring's planting: erosion.

"Each little raindrop is like a little bomb," said James Pingry, a U.S. Soil Conservation Service agronomist."Anywhere there's been drought the risk of erosion is greater," said Scott Argabright, an agronomist at the Soil Conservation Service's Midwest National Technological Center in Lincoln, Neb.

In Iowa, conservationists said Tuesday the record pace of corn and soybean harvests by farmers trying to prevent further crop damage will only accelerate fall plowing and other fieldwork to prepare for next spring.

Stripping away the residue of the last crop and turning the dirt over always has the risk that wind and water erosion will carry off exposed topsoil.

"But this year's drought left the soil drier than usual. That means if the land is plowed it will be especially vulnerable to wind erosion," Jim Ayen, state resource conservationist for the Soil Conservation Service of the U.S. Department of Agriculture, said in an advisory urging farmers not to plow this fall.

"There's a definite correlation between plowing or tilling in the fall and moisture loss," said James Gulliford, director of the Iowa Department of Agriculture's Soil Conservation Division. "The best way to conserve that moisture is not to till."

In addition to unusually dry conditions, drought damage to crops reduced the residue in the soil after the harvest, cutting the natural protection available to soil left unplowed, Argabright said.

Dry soil also is vulnerable to greater than usual water erosion. Raindrops break bare soil into tiny particles, and water carries the particles away, Pingry said.

Fall field work is often prompted by a belief that some soil types can be better prepared for the spring by removing crop residue and turning the soil over, a practice Gulliford said he does not believe is supported by research.

Other farmers use as much time as available before bad weather sets in to prepare fields out of fears that a wet spring will delay planting preparations.

"We don't feel there's proven economic evidence that fall plowing pays off," Gulliford said.

While Iowa farmland was saturated with moisture when last spring's planting season began, a report Monday said only 2 percent of the subsoil and 46 percent of the topsoil had adequate moisture. A year ago, 81 percent of the subsoil and 90 percent of the topsoil had adequate moisture and an additional 10 percent of the subsoil and 8 percent of the topsoil had surplus moisture.

In Minnesota, the year's heaviest weekly rain fell last week and was quickly soaked into the ground. Unlike downpours in normal times, there was very little standing water in fields.