Carbon Sequestration in Reclaimed Mined Soils of Ohio

Abstract

Assessment of soil organic carbon (SOC) sequestration potential of reclaimed minesoils (RMS) is important for preserving environmental quality and increasing agronomic yields. The mechanism of physical SOC sequestration is achieved by encapsulation of SOC in spaces within macro and microaggregates. The experimental sites, owned and maintained by American Electrical Power, were characterized by distinct age chronosequences of reclaimed minesoils and were located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. These sites were reclaimed both with and without topsoil application, and were under continuous grass or forest cover. In this report results are presented from the sites reclaimed in 1994 (R94-F), in 1987 (R87-G), in 1982 (R82-F), in 1978 (R78-G), in 1969 (R69-F), in1956 (R56-G), and from the unmined control (UMS-G). Three sites are under continuous grass cover and three under forest cover since reclamation. The samples were air dried and fractionated using a wet sieving technique into macro (> 2.0 mm), meso (0.25-2.0 mm) and microaggregates (0.053-0.25 mm). The soil C and N concentrations were determined by the dry combustion method on these aggregate fractions. Soil C and N concentrations were higher at the forest sites compared to the grass sites in each aggregate fraction for both depths. Statistical analyses indicated that the number of random samples taken was probably not sufficient to properly consider distribution of SOC and TN concentrations in aggregate size fractions for both depths at each site. Erosional effects on SOC and TN concentrations were, however, small. With increasing time since reclamation, SOC and total nitrogen (TN) concentrations also increased. The higher C and N concentrations in each aggregate size fraction in older than the newly reclaimed sites demonstrated the C sink capacity of newer sites.