Drainage Management, Climate Change and Soil Health.

European settlement resulted in conversion of most of the tallgrass prairie ecosystem in Minnesota to crop production. This ecosystem was ideally suited to highly productive and profitable agricultural production once the land was artificially drained through subsurface drainage to alleviate poorly drained soil conditions. These major changes in land use and land management are important factors in observed differences in soil physical and chemical properties of Mollisols in Minnesota. This experiment compared soil physical and chemical properties between a cultivated agricultural field and an adjacent remnant prairie; both which developed under identical soil forming processes. Both land uses occur within the same soil map unit, a poorly drained Havelock clay loam (fine-loamy, mixed, superactive, calcareous, Mesic Cumulic Endoaquol). In 2005, 48 undisturbed soil cores (0 - 1.2 m depth) were collected from the cultivated field and 12 from the remnant prairie and analyzed by horizon. Bulk density in the surface horizon was found to be significantly lower for the soil under prairie vegetation (1.11 Mg m^-3) compared with the cultivated soil (1.30 Mg m^-3). The bulk density in the two measured subsurface horizons of the prairie (1.12, and 1.10 Mg m^-3, respectively) was significantly lower than those for the cultivated soil (1.30 and 1.32 Mg m^-3, respectively).  Total porosity in the surface horizon of the prairie was significantly higher (0.58 %, respectively) than that in the cultivated soil (0.51 %). For the two subsurface horizons, total porosity was greater for the prairie soil (0.58 and 0.58 %, respectively) than for the cultivated soil (0.51 and 0.50 %, respectively). Soil organic matter, total carbon (C), nitrogen (N), CEC and extractable soil magnesium (Mg) and zinc (Zn) were lower and soil pH, extractable soil phosphorus (P), potassium (K), and calcium (Ca) were higher under the cultivated field. These results suggest that land use and land management alterations have altered soil physical and chemical properties. It is useful to evaluate changes in soil properties and relate them to past and future management practices.