Carbon storage and minesoil properties in relation to topsoil applications techniques

Reclaimed minelands could act as C sinks, but shallow soil, nutrient deficiency, and compaction could limit C accretion in these ecosystems. This study evaluated the impact of topsoil application techniques on total C storage (tree biomass and soil organic C [SOC]) in 15-yr-old experimental plots established on reclaimed land in southeastern Ohio. Treatments included topsoil (graded overburden [OV] and standard [ST] and ripped topsoil [RT]) and P fertilization (0 and 2.24 Mg ha(-1) of rock phosphate). One half of each plot was planted with Austrian pine (Pinus nigra J.F. Arnold ssp. nigra) and the other half with green ash (Fraxinus pennsylvanica Marshall). A significant effect of topsoil application on tree growth and SOC was noted. In green ash plots, aboveground biomass was always <3.4 Mg C ha(-1), but in Austrian pine stands it averaged 10.3, 15.2, and 2.1 Mg C ha(-1) in the ST, RT, and OV plots, respectively. The pool of recent SOC (after discounting geogenic C) was in the order: ST (34.9 Mg C ha(-1)) > RT (29.8 Mg C ha(-1)) > OV (17.8 Mg C ha(-1)). The lower SOC in RT than in ST plots was attributed to enhanced C mineralization by soil ripping, but with the fast-growing Austrian pine, this SOC deficit was compensated by a greater (by 34.9 Mg C ha(-1)) standing tree biomass in the RT plots, resulting in comparable total C storage with either ST or CT. With the slow-growing green ash, however, total C storage was significantly lower in RT (27.9 Mg C ha(-1)) than in ST (37.4 Mg C ha(-1)) plots. Thus, the impact of topsoil application technique on C storage in these aggrading ecosystems is largely determined by tree growth and productivity.