Physical reconstruction of mine tailings after surface mining mineral sands from prime agricultural land

Minable quantities of heavy minerals occur in prime agricultural lands of t he Atlantic Coastal plain, We evaluated the use of yard waste compost to re claim tailings mined front these lands. A 30 x 60-m area was excavated to a depth of 5 m to establish a reclamation study site. Soils were removed, tr eated in a manner simulating the separation of the mineral sands, and retur ned in a slurry form, Undisturbed natural soils, Hapludults and Paleudults, have sand and loamy sand surface horizons. Mining these soils and redistri buting the tailings as a slurry resulted in sandy loam and sandy clay loam textures. Treatments established in the tailings were: unamended tailings; tailings amended with 23 to 270 t/ha compost; and tailings capped with 45 c m of topsoil, Selected treatments were sampled and analyzed to test for dif ferences in the physical properties related to treatment. Gravimetric water contents of tailings amended with 135 t/ha compost were significantly high er (at the 0.05 level) than unamended tailings, tailings capped with top so il, or the natural soil. Mechanical resistance values recorded in the Fall for tailings amended with 135 t/ha of compost were lower than the unamended tailings and tailings capped with topsoil, Mean hydraulic conductivity (K- sat) and porosity values for tailings amended with 135 t/ha compost were hi gher than the natural soil surface horizons. Tailings amended with as littl e as 45 t/ha compost had higher porosity (48%) and lower bulk density (1.38 g/cm(3)) values than the natural soil surface (45% and 1.43 g/cm(3)). Tail ings capped with topsoil had the highest bulk density (1.64 g/cm(3)) and lo west porosity (38%) and Ksat (0.13 cm/hr), suggesting that this reclamation approach may not be the best way to try to reclaim the tailings. Average c orn yields for tailings amended with compost were higher than those for tai lings capped with topsoil or unamended tailings. Results suggest that mine soils can be constructed with excellent physical properties with regard to plant growth by amending tailings with yardwaste compost.