Characterizing organic carbon storage in experimental agricultural ditch systems in northeast Arkansas

Authors: ISEYEMI, OLUWAYINKA - Arkansas State University; FARRIS, JERRY - Arkansas State University; Moore, Matthew; GREEN, V - Arkansas State University; Locke, Martin; CHOI, SEO-EUN - Arkansas State University

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2018
Publication Date: 5/1/2019
Citation: Iseyemi, O.O., Farris, J.L., Moore, M.T., Green, V.S., Locke, M.A., Choi, S. 2019. Characterizing organic carbon storage in experimental agricultural ditch systems in northeast Arkansas. Soil Science Society of America Journal. 83(3):751-760. https://doi.org/10.2136/sssaj2018.10.0370.
DOI: https://doi.org/10.2136/sssaj2018.10.0370

Interpretive Summary: With increased research emphasis on climate change and carbon sequestration in agricultural ecosystems, the current study was undertaken to attempt to quantify potential carbon storage capability of vegetated agricultural drainage ditches. Soil organic carbon and bulk density measurements were taken seasonally and spatially among replicated ditches comparing carbon sequestration of ditches with / without low-grade weirs as well as ditches with / without vegetation maintenance (i.e. mowing). Neither the presence of low-grade weirs nor vegetation maintenance had an effect on the seasonal (summer and winter) soil carbon concentrations. High pools of carbon were collected in the vegetated ditches, indicating their ability to sequester carbon in the environment. This demonstrates another positive ecosystem service provided by agricultural drainage ditches.

Technical Abstract: Agricultural drainage systems are often considered as primary wetlands within the production landscape. In addition to having definitive characteristics, these drainage systems are capable of many ecological functions, including carbon sequestration, wildlife habitat, flood control and edge of field nutrient filtration. This study investigated the potential for carbon sequestration within replicated mowed and unmowed experimental conventional and controlled (with weirs) agricultural drainage systems. The study analyzed and compared spatial and seasonal (temporal) variation in soil organic carbon concentration (g C kg-1) and organic carbon pool (kg C m-2) within 3 cm soil depth between ditch treatments. Composite soil samples were taken from five sampling points (inflow, 10 m, 30 m, 50 m and 60 m (outflow)) within each ditch treatment. Soil organic carbon concentrations were quantified through combustion of organic matter 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 carbon concentration in ditches with weirs was similar to mean soil carbon concentration in ditches with no weirs (16.68 ± 0.49 g C kg-1 vs. 16.47 ± 0.46 g C kg-1 in summer; 14.47 ± 0.75 g C kg-1 vs. 16.27 ± 0.72 g C kg-1 in winter). Likewise, the average carbon content in mowed ditches was similar to that in unmowed ditches from both seasons (16.54 ± 0.52 g C kg-1 vs. 16.60 ± 0.44 g C kg-1 in summer; 16.57 ± 0.34 g C kg-1 vs. 15.37 ± 0.53 g C kg-1 in winter). Similar bulk densities (0.67 Mg m-3, on average) and organic carbon contents in ditches furnished comparable carbon pools. The mean carbon pool in ditches with weirs was similar to the mean carbon pool in ditches with no weirs (28.08 ± 0.75 kg C m-2 vs. 27.88 ± 0.68 kg C m-2 in summer; 26.44 ± 1.56 g C kg-1 vs. 30.24 ± 1.40 g C kg-1 in winter). The studied experimental drainage ditches can therefore be considered for their contributions to the carbon sink, suggesting agricultural drainage systems offer a suitable environment for carbon sequestration.