A Soil-Landscape Model for Post-Settlement Alluvium and Soil Organic Carbon Predictions In a Glaciated Landscape of Minnesota.

Agricultural tillage increases soil erosion and the subsequent redistribution of sediment and soil organic C. Understanding the movement of soil organic carbon in agricultural landscapes is important because it is a critical component in the landscape-scale soil organic carbon balance. A suitable soil-landscape model can help us to understand the spatial redistribution of soil organic carbon and soil organic carbon dynamics under agricultural systems. Our current research on hilly landscape in Des Moines Lobe sediments in Minnesota showed that soils transported by agricultural-induced erosion were largely redistributed downslope to footslope and toeslope positions on the same hillslope. The thickness of this post-settlement alluvium (PSA) and the spatial distribution of soil organic carbon were well correlated with digital terrain attributes. We aim to build a soil-landscape model based on terrain attributes for the spatial redistribution of soil C in this closed depressional landscape. The following objectives will be met: 1. Build a geoprocessing tool to calculate upslope terrain characteristics that contribute to any specific cell in the digital representation of the landscape; 2. Identify terrain attributes that control the spatial distribution of PSA and soil organic carbon; 3. Develop spatial models for PSA and soil organic carbon redistribution based on field measurements and terrain attributes.   Terrain attribute values derived from a 1-m horizontal resolution digital elevation model will be analyzed for their correlations with both soil organic carbon and PSA  from field measurements. Models of the spatial distribution of PSA and redistribution of soil organic carbon will be developed and validated against field data sampled across this physiographic region.