The accumulated organic matter from centuries produce a rich, dark prairie soil (mollisol).

With its combination of excellent transportation and remarkably fertile prairie soils, Mattoon expanded rapidly.

And while the method proved reliable for farmland, the researchers say more work is needed make it useful for prairie soils.

The ditches around the circles penetrated the hardpan, helping to drain the prairie soil.

Euro-Americans arrived in the 1820s and recognized the fertile prairie soil as ideal farmland.

The rich, dark prairie soils make the township valuable as farmland.

Like corn and wheat, Wright's vision had grown up on prairie soil.

The prairie soil is part of one of the world's most fertile growing areas.

The parent material of most prairie soil was deposited during the last glacial advance that began about 110,000 years ago.

Wind based loess deposits also form an important parent material for prairie soils.