The Modern Relevance of Catenas to Pedology in Iowa.

Iowa is one of the most intensely farmed states in the U.S., which brings to question whether human impacts on soil catenas in the state’s rural areas are minor or dominant pedogenic influences.  Answering this question is crucial to evaluating the modern relevance of the traditional catena model. To address this, four benchmark catenas located on the Des Moines Lobe in Iowa were re-examined to determine the changes within the soil landscape resulting from decadal scale agriculture. All of the study sites are closed-basin catenas located within 40 km of each other with a parent material of Late Wisconsinan glacial till. Soil cores to a depth of one to two meters were taken at 30 meter intervals along one transect for each of the four catenas.   Core descriptions and laboratory analyses are ongoing.  Preliminary results indicate that some soil properties such as texture have not changed much over a period of decades, while other properties such as pH and thickness of mollic epipedon have changed significantly. This indicates that anthropogenic impacts due to agriculture are a significant pedogenic influence, which is decreasing the scientific value of the current catena model. We anticipate that as humans continue to progressively alter the landscape, the current catena model will no longer be sufficient to predict soil distribution.