64-11 Evaluating the Effects of Topographic Position and Land Management on Soil Carbon Stock and Soil Health

Session: Emerging Voices in Soil and Paleosol Science (Posters)

Presenting Author:

Authors:

Abstract:

During the last ice age, ice sheets advanced and retreated across the upper Midwest, leaving behind a landscape characterized by poorly drained hummocky topography. Well-aerated soils have formed on uplands, and lowlands are dominated by hydric soils and ponded water is common. This landscape, known as the Prairie Pothole Region, encompasses one of the most unique wetland-grassland ecosystems in the world. These wetlands and hydric soils have potential to store large quantities of carbon, but many have been drained and cultivated for decades to increase agricultural productivity. Conventional agricultural practices have increased soil erosion while degrading soil structure and water holding capacity, further reducing carbon storage potential. 

The purpose of this study is to determine how land management practices and topographic position affect soil carbon and soil health. Soil cores were collected to a depth of 30 cm from six topographic positions among three land management practices. Topographic positions include lowlands, toeslope, footslope, backslope, shoulder, and summit; land management practices include cultivated cropland, conservation tillage cropland, and Conservation Reserve Program (CRP) enrolled grassland. Accounting for topography is critical in this gently undulating landscape, as topographic position influences geomorphic processes and pedogenesis. Cores were analyzed for a host of soil health indicators including organic matter, moisture, and nutrient contents, pH, bulk density, microbial respiration, aggregate stability, and particle size.  

While most data are pending, preliminary results indicate there are distinct differences in soil properties based on topographic position and land management practices. Moisture content is higher and bulk density lower in the lowland position compared to uplands (i.e., summit, shoulder, and backslope). Land management also has a distinct impact with CRP grasslands having higher aggregate stability and microbial respiration than conventional and no-till cropland. 

Initial data highlight the importance of topographic position on soil health, an often-overlooked variable. Additional pending data will provide further insight into the role of topographic position when implementing conservation and restoration practices in agricultural landscapes. 

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9947

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.