Landscape position effect on selected soil physical properties of reconstructed prairies in southcentral Iowa

Abstract

Changes in land use and alteration of the ecosystem can significantly affect soil physical, chemical, and biological properties. In this study, changes in soil organic carbon (SOC), root biomass, bulk density (ρb), water stable aggregates (WSA), and infiltration rates were examined in reconstructed prairies varying in age and landscape position. The objective of the study was to determine the potential of landscape position effect on these selected soil properties in reconstructed prairies. Findings show that SOC increased as years since prairie establishment increased and had a positive correlation with infiltration rate and WSA. The opposite was true for ρb, where it decreased as prairie age increased and negatively correlated with SOC. However, the effects of SOC and ρb on infiltration rates varied by landscape slope position and age of prairie establishment. Root biomass, SOC, and WSA had decreased, while ρb increased at the midslope compared to the summit and toe-slope positions resulting in lower infiltration rates. Although the summit and the toe-slope positions had similar soil properties, infiltration rates were much greater in the toe-slope position. This was ascribed to the toe-slope position's superior WSA, due to greater SOC concentrations. In general, this study shows that over time, increases in SOC did promote aggregate formation and lower ρb, creating more permeable soil surfaces in these reconstructed prairies. However, better soil conservation practices that reduce soil surface water runoff in the midslope in particular are needed during the first few years of prairie establishment.