The number of Iowa farmers practicing soil conservation is leveling off after years of growth, a new study suggests, even as federal regulators watch the state's efforts to clean dirty rivers and lakes.
Silt is the top pollutant of Iowa's waterways.
Lakes fill with silt, and chemicals that come with the soil cause algae-related fish kills. The U.S. Environmental Protection Agency is considering whether Iowa is doing enough to clean 159 river stretches and lakes that have been declared impaired. Through the 1980s and into the 1990s, Iowa farmers increasingly used such soil-saving techniques as leaving corn stubble in fields. A coalition of farm-related groups that sponsored the new survey feared farmers had stopped leaving corn stubble. A check in 1998 had found a 12 percent drop in conservation practices in a year.