ABSTRACT
Summary The research objectives were (1) to determine the effects of topsoil on establishment of seeded vegetation on strip-mine spoils, (2) to determine the effects of depth of topsoil placed over spoil on growth of herbage and roots, and (3) to evaluate 17 grass species grown on topsoil and mine spoil. In a field study in northwestern Colorado, a seed mixture of range grasses, forbs, and shrubs was drilled on five (0, 10, 20, 30, and 46 cm) depths of topsoil placed over surface coal-mine spoil, and the effect of topsoil depth on species establishment was measured. In a greenhouse study, the effects of five depths of topsoil placed over spoils on herbage and root yields of intermediate wheatgrass (Agropyron intermedium [Host] Beauv.) and wheat (Triticum aestivum L.) were determined. In a second greenhouse study, 17 grasses were planted in 23 cm of topsoil over spoil and in spoil alone to evaluate species differences in herbage yield, root yield, and root distribution in topsoil and underlying spoil. In the field planting, stand establishment averaged 1.9 times better on all topsoil depths than on spoil alone, and the density of the seeded stand increased linearly as topsoil depth increased. In the greenhouse, herbage yield increased linearly with the increase in topsoil depth. Root production by both species was greater in topsoil than in underlying spoil; however, intermediate wheatgrass produced two to four times more root weight in spoil than did wheat. In the second greenhouse study, the 17 species were divided into 3 groups based upon productivity, rooting patterns, and other characteristics.
354Depth of topsoil and species selection should be considered for optimum revegetation success. The greater the topsoil depth is, at least up to 46 cm, the denser the seeded stand will be in the Held, and the greater the herbage and root production will be in the greenhouse. Species can be selected that will provide high root production, good rooting into the underlying spoil, maximum herbage yield, or a combination of these qualities.
