Inventorying Dynamic Soil Properties across Iowa's Catenas and Land Uses.

Over the past decade we have completed numerous projects across Iowa to discern how pedons, landscapes and watersheds are spatially altered by long-term land use. We remain especially interested in quantifying the rates and depths of change in bulk density, soil structure, hydraulic conductivity, soil organic carbon content (SOC), soil organic nitrogen content, pH, texture and horizonation as well as documenting erosion and sedimentation. Our data show management has significantly affected each property, often to greater depths and over wider extent than we initially hypothesized. For example, cropped Medisaprists in Iowa are literally thinning at an average 3 cm yr-1 rate as their O horizons degrade. Alternatively, epipedons become significantly thicker and enriched in SOC when severely eroded hillslopes are stabilized via conservation reserve plantings. Interestingly, epipedons have also become significantly thicker with row cropping across stable soilscapes. In total we interpret our projects as showing soil properties are more dynamic than classically thought in pedology and that integration with hydrology and field biology is critical to the future of soil science.