Geochemical Factors Affecting Plant Growth in Reclamation

Reclamation under the strict requirements of the federal Surface Mining Control and Reclamation Act of 1977 requires a high level of knowledge of plant growth r e q u i r e m e n t s in r e l a t i o n to geochemical factors on each mine site. A desirable reclamation goal would be to consider all feasible alternatives for creating productive soils and attractive landscapes. The raw materials for achieving such a goal are the rocks and unconsolidated overburden that are commonly termed spoil after mining. Misdirected reclamation tasks can introduce unnecessary costs, lessen success of revegetation, and deny opportunities for building a land better than before mining. In this paper we focus on the geochemical processes, to which the various minerals contribute on an uneven scale. Sulphur-containing rocks and minerals dominate the geochemical processes. We do not evaluate the highly important role of soil physical conditions in reclamation. In many respects the soil-plant relationships on mine spoils can be understood as an extension of knowledge from traditional agricultural studies. Agricultural soils are, however, composed for the most part of materials which have been exposed to weathering processes for thousands of years. They typically are leached and ion-poor. Mine spoils contain large amounts of minerals freshly exposed to weathering; these minerals may release large quantities of ions. Spoils underlying topsoil are subject to these same oxidative weathering processes, although probably at slower rates. Spoil thus differs from other midwestern soils in that it involves an ion-rich environment.