Carbon Sequestration in Reclaimed Mined Soils of Ohio

Abstract

This research project is aimed at assessing the soil organic carbon (SOC) sequestration potential of reclaimed minesoils (RMS). The experimental sites were characterized by distinct age chronosequences of reclaimed minesoil and were located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. These sites are owned and maintained by Americal Electrical Power. These sites were reclaimed (1) with topsoil application, and (2) without topsoil application, and were under continuous grass or forest cover. Three core and three bulk soil samples were collected from each of the experimental site and one unmined site (UMS) for 0-15 cm and 15-30 cm depths and soil bulk density ({rho}{sub b}), texture, saturated hydraulic conductivity (Ks), volumes of transport (VTP) and storage (VSP) pores, available water capacity (AWC), pH and electrical conductivity (EC), SOC, total nitrogen (TN) concentrations and stocks were determined. The preliminary results from sites reclaimed with topsoil and grass indicate that sand content was highest (24%) and clay content was lowest (17%) for site reclaimed in 2003 (R03) for 0-15 cm depth. The {rho}{sub b} was highest for R03 (1.24 Mg m{sup -3}) than sites reclaimed in 1987 (R87; 1.02 Mg m{sup -3}), 1978 (R78; 0.98 Mg m{sup -3}) and UMS (0.96 Mg m{sup -3}) for 0-15 cm depth. No significant differences were observed in Ks, VTP, VSP, AWC among these sites (P<0.05). For 15-30 cm depth {rho}{sub b} varied in the order R03 (1.61 Mg m{sup -3})> R87 (1.42 Mg m{sup -3}) = R78 (1.40 Mg m{sup -3}) = UMS (1.34 Mg m{sup -3}). Soil pH was > 5.5 and EC < 4 dS m{sup -1} for all sites and depths and was favorable for grass growth. The SOC and TN stocks were lower in R03 (3.5 Mg ha{sup -1} and 0.6 Mg ha{sup -1}; respectively) than R78 (30.1 Mg ha{sup -1} and 1.6 Mg ha{sup -1}) and UMS (18.7 Mg ha{sup -1} and 1.8 Mg ha{sup -1}) for 0-15 cm depth. The SOC and TN stocks were also lower in R03 (2.9 Mg ha{sup -1}and 0.8 Mg ha{sup -1}; respectively) than R87 (22.5 Mg ha{sup -1} and 1.1 Mg ha{sup -1}) and R78 (22.2 Mg ha{sup -1} and 1.1 Mg ha{sup -1}) for 15-30 cm depth. The SOC stocks in soils reclaimed with topsoil application and under grass increased from a base line value of 1.85 Mg ha{sup -1} at a rate of 0.69 Mg ha{sup -1} y{sup -1} topsoil in 0-15 cm depth. For 15-30 cm depth, the SOC stocks increased from a baseline value of 1.07 Mg ha{sup -1} at a rate of 0.73 Mg ha{sup -1} y{sup -1}. For sites reclaimed without topsoil application, {rho}{sub b} was significantly different between sites reclaimed in 1957 (R57; 1.6 Mg m{sup -3}) under grass and forest (R57-F; 1.2 Mg m{sup -3}) for 15-30 cm depth only. No significant differences were observed in clay content, Ks, VTP, VSP, AWC, SOC and TN stocks among these sites (P<0.05). Taking SOC stocks of R03 as baseline, the SOC stocks for sites reclaimed without topsoil increased from 13 to 19 times in R57 and R57-F in 0-15 cm soil depth and 14 to 20 times in 15-30 cm depth. These results are preliminary and will be validated further when detailed soil sampling is carried out during April-Sept. 2004.