VARIABILITY OF SOIL ORGANIC CARBON IN TWO RECLAIMEDSITES IN SOUTH EASTERN OHIO

摘要

Knowledge of spatial variability is essential for assessing the true soil organic carbon (SOC) content and the sequestration potential of reclaimed minesoils (RMS). Two experimental sites were selected for determining the spatial variability of some soil properties including soil organic C (SOC) stock. Both sites located in Guernsey County of Ohio were reclaimed in 1978 with topsoil application and are under grass and forest cover, respectively. Soil bulk density (rho_b), SOC, total nitrogen (TN) concentrations and stocks were determined for both sites for 0-15 cm, 15-30 cm, and 30-50 cm depths. In the Forest site, the statistical variability of rho_b was low in all three depths. The rho_b increased with depth and ranged from 0.88 Mg m~(-3) to 1.16 Mg m-3 for 0-15 cm, 0.91 Mg m-3 to 1.32 Mg m~(-3) for 15-30 cm, and 1.37 Mg m~(-3) to 1.93 Mg m~(-3) for 30-50 cm depths. The variability in rho_b was also low in Grass site and ranged from 0.82 Mg m~(-3) to 1.18 Mg m~(-3) for 0-15 cm, 1.04 Mg m~(-3) to 1.37 Mg m~(-3) for 15-30 cm, and 1.18 Mg m~(-3) to 1.83 Mg m~(-3)for 30-50 cm depths. The rho_b showed strong spatial dependence for 0-15 cm depth only in the Forest site (nugget:sill ratio = 20). The statistical variability of SOC concentrations and stocks were high for all depths in both sites (CV > 0.36). The SOC stocks also had strong spatial dependence for 0-15 cm and 30-50 cm depths (nugget:sill ratio < 17) and moderate to strong dependence for 15-30 cm depth in the Forest site (nugget:sill ration=24). In contrast, in Grass site, rho_b was weakly and SOC stocks moderately spatially dependent for all depths. Variability did not follow a consistent trend and both short (mostly) and long range variability were observed. These results suggest that the management effects are important and assessment of spatial variability is necessary for the correct assessment of SOC accretion in reclaimed minesoils.