Characterizing Organic Carbon Storage in Experimental Agricultural Ditch Systems in Northeast Arkansas

Agricultural ditches are capable of many ecological functions, including flood control and edge of field nutrient filtration. This study investigated the potential for carbon sequestration within mowed and unmowed experimental conventional and controlled (with weirs) agricultural drainage ditches. The study analyzed and compared spatial and temporal variation in soil organic carbon (OC) concentration (g C kg–¹) and OC pool (kg C m–²) within a 3-cm soil depth between treatments. Soil OC concentrations were quantified through combustion of organic matter (OM) at 400°C in a muffle furnace for 16 h using the loss on ignition (LOI) method. Soil bulk density was also determined for each ditch treatment. In both summer and winter, mean soil C concentration in ditches with weirs was similar to mean soil C concentration in ditches with no weirs (16.68 ± 0.49 vs. 16.47 ± 0.46 g C kg–¹ in summer; 14.47 ± 0.75 vs. 16.27 ± 0.72 g C kg–¹ in winter). Similar bulk densities (0.67 Mg m–³, on average) and OC contents in ditches furnished comparable C pools in ditches with weirs and no weirs respectively (28.08 ± 0.75 vs. 27.88 ± 0.68 kg C m–² in summer; 26.44 ± 1.56 vs. 30.24 ± 1.40 g C kg–¹ in winter). The studied drainage ditches can therefore be considered for their contributions to the C sink, given the high values of C pool observed in the ditch treatments. This suggests agricultural drainage ditches can offer a suitable environment for C sequestration.