1 l Wisconsin’s soils were first mapped more than a century ago. The first soil map of Wisconsin was also the first ever made in the United States. It was produced in 1882 by geologist T.C. Chamberlin. In 1926, CALS soils professor Andrew Whitson created the second state soil map for his book Soils of Wisconsin. The third map followed 50 years later, compiled by eminent CALS soils professor Francis Hole. Since that time much new information and many insights have been gained, and these have been summarized in a fresh edition of The Soils of Wisconsin.
2 l The soils of Wisconsin are highly diverse. Nearly 80 percent of the state is covered with glacial deposits that differ in texture, composition, thickness and age (the Driftless Area, in western Wisconsin, was not glaciated in the most recent glacial period). There is a strong relationship between the soils and parent materials. The history of human impacts on soils in Wisconsin extends back 13,500 years but became intensified during the Late Woodland period (1,600 to 500 years Before Present) when fires were used to clear land, and further intensified in the mid-1800s when European settlers arrived and land clearing and large-scale crop production began.
3 l Many of Wisconsin’s soils are unique. There are more than 700 soil series (groups of soils with similar properties) in Wisconsin, and of these, 20 percent are considered endemic, having developed here through a unique combination of geology, plant communities and other factors. The “tension zone” between Wisconsin’s northern and southern forests contains 40 percent of these endemic soils while covering just 13 percent of the state’s land area. This zone also marks a transition not just in vegetation but in soil. The soils of the prairie, or Mollisols, mainly occur below the tension zone, and acid Spodosols, which often are forested, exist above it.
4 l Soils are affected by changes in climate. The melting of glaciers 11,000 years ago is a climatic event that affected Wisconsin’s soils, depositing millions of tons of glacial till and windblown, silty soil. For the future, we expect rising temperatures and increasing rainfall that will affect our soils and land use. In the winter, soils will cool more because of thinner snowpacks and less protection from freezing. The warming up will result in land use changes. Corn and soybean, for example, might be grown in areas that previously were unsuitable.
5 l Our soils yield profits. The soils in Wisconsin have a high yield potential and support an $88 billion industry. We observe highly significant correlations between the soil and such economic parameters as agricultural land value sales and adjusted gross income in every county of the state.
James Bockheim is professor emeritus and Alfred Hartemink is professor and chair of the Department of Soil Science. Their new edition of The Soils of Wisconsin, published in spring 2017, is dedicated to Francis Hole.