FIELD STUDY IN A PROJECT-BASED SOILS COURSE

The five factors that affect soil development—parent material, time, topography, climate, and organisms—served to focus the study of local soils in a project-based, mid-level geology course. Pairs of students investigated a single soil-formation factor as it pertains to local areas, and each pair presented results to their peers. The class then chose two field sites. To investigate the effects of topography, they selected a maple-forested, east-facing slope underlain by Ordovician sandstone. They reasoned that time and climate would be constant for all points on the slope. To study the effects of organisms, they chose a flat, College-managed sedge meadow; their transect traversed areas dominated by the invasive reed canary grass, native sedges, and oak elm woodlands.

In the field, students described the area, plotted coring sites on maps, and recorded data from coring activities. Students worked as a group to collect five cores at each of the two sites; they divided into pairs to complete detailed lab study of each core (grain-size analyses, percent organic matter, nitrate and phosphate concentration, pH, water-holding capacity, and calcium carbonate content), write up results, and present findings to the class. I compiled their data, the results of which served as fodder for further discussion.

Field aspects of the course put the lab study into a context—students were testing predictions that they had made by researching and choosing sample sites. They were better able to understand and discuss the results. For example, whereas findings from the slope study supported their predictions, those from the flat area were difficult to interpret. In part, the sedge-meadow results showed the effects of microtopography, which determined water availability and thus plant type. The personal experience of being in the field and sinking in the mud of the wetter areas allowed them to propose microtopography as a confounding variable. In addition, coring required a group effort, which further built camaraderie that carried over into the classroom.