Mineralizable Soil Organic Carbon Dynamics in Corn-Soybean Rotations in Glaciated Derived Landscapes of Northern Indiana

The concerns about climate change have increased interest in understanding differences in soil carbon pools and availability. The objective of this study was to assess total Soil Organic Carbon (SOC) and mineralizable SOC (Cmin) dynamics and spatial distribution as controlled by slope position, in glaciated northern Indiana. We collected 210 soil samples from the 0 to 25 cm surface layer along 10-point transects along a soil catena. Total SOC was determined by dry combustion and Cmin by incubation. The spatial distribution of total SOC followed patterns related to soil wetness. Overall, the depression areas stored between 50 and 141 Mg C ha−1 or between 50 and 68 % more total SOC when compared to the drier areas. After 28 days of incubation (Cmin), depressions released 1.2 Mg C ha−1, which was significantly more than the drier areas at 0.8 Mg ha−1. These differences indicate the potential of wetter areas, to store C if converted to C accruing management practices. The mean daily rate of C-CO2 evolved decreased exponentially during the first 28 days from 1.5 to 0.2 μg g−1 h−1. The management of these targeted areas can potentially increase soil C stock in arable lands and assist managers in developing systems that will sequester soil carbon.