"Exploring Soil Organic Carbon Methodology and Variability in Rockbridge County Pastures"

Iszak Morgan, Thesis 2020

"Exploring Soil Organic Carbon Methodology and Variability in Rockbridge County Pastures"
Advisor: David Harbor

Abstract: Climate change has pushed the exploration of new ideas with the goal of lowering the carbon footprint. Of these ideas, carbon sequestration is one of the more promising methods. To determine if carbon is being sequestered, the methods for determining organic carbon in soils must be accurate and repeatable. Two common methods are combustion through loss on ignition and using an elemental analyzer. We compared these two methods with Rockbridge County, VA soils, to determine which method provides the most accurate and repeatable results. Two inorganic carbon methods, loss on ignition and acid digestion, were also tested to convert total carbon to organic carbon in the elemental analyzer. Soil samples were collected and tested from a local farm practicing regenerative agriculture grazing procedures. Both methods were employed for each sample and the results were compared. In a vast majority of samples, the loss on ignition method reported higher organic carbon results than the elemental analyzer. However, this result is likely due to overestimates when determining inorganic carbon in samples for use in the elemental analyzer. The overestimate can be mitigated by changing the method for inorganic carbon from acid digestion to a modified acid digestion or a pressure-calcimeter. To most efficiently, accurately, and repeatably measure carbon in Rockbridge County soils, the elemental analyzer method stands out as the best method.

Full thesis available. Contact the Geology Department at 540-458-8800.