(a) Soil in central Iowa with dark, organic-matter-rich topsoil. Iowa's average topsoil depth decreased from 35-45 cm to 15-20 cm during the 20th century due to farming. (b) Severe gully erosion ...

When European-American settlers first began ploughing in Iowa, they found the weather and local geology had combined this organic mulch with sand and silt to form a nutrient-rich type of soil ...

As of late January, soil temperatures show a frost depth of around 17" in Eastern Iowa, and 4-inch soil temperatures well below freezing. Whether this has a negative impact depends on future ...