Monday, November 13, 2006 - 2:05 PM

Physical and Chemical Properties of Sediments Following Extended Inundation of Agricultural Soil.

Ana J. Wells and Nick J. Balster. Univ of Wisconsin, Madison, 1525 Observatory Dr, Madison, WI 53706

The removal of dams and their subsequent restoration to native landscapes is a growing practice in the Midwestern United States. However, many questions regarding the physical and chemical variability of these lacustrine sediments need answers to inform our restoration efforts. For 40 years, a topographic depression in southern Wisconsin was dammed and subsequently inundated by natural spring waters and surrounding agricultural runoff. In 2003, the Dam was removed and the basin drained to support restoration to native prairie. Using this opportunity to study relationships between plant density, soil, and hydrologic processes, we seeded prairie vegetation (60% forbs, 40% grasses) in four replicates of varied seed density across a 1.5-acre plot. Preliminary sampling showed significant spatial variation in physical and chemical properties of the sediments. For example, the average depth of the deposited sediments was 42.9 cm, ranging from 13 cm (nearest the dam) to 72 cm (basin center). Moreover, bulk density decreased from west (nearest the dam) to east in both surface sediments and soil at 30 cm. In addition to these measurements, we also quantified the variation in hydraulic conductivity and a host of chemical constituents across the basin. From these results, we highlight the heterogeneous, yet quantifiable pattern in soil characteristics and demonstrate the necessity of their quantification to restoration success.