A root growth study used to examine the suitability of two grasses for stabilizing toxic mine wastes.

Abstract

The rooting ability of Dactyloctenium geminaturm and Paspalum vaginatum was studied in a pot trial using mining wastes (slimes) containing a total 1 980 ppm arsenic and a specific conductivity of 16 050 micromhos. Under the conditions of the pot trial, P. vaginatum produced at least double the biomass of roots and shoots when compared with D. germinatum. The effect of compounded fertilizer (8N: 15P: 10K) at 1 000 kg/ha equivalent on shoot development was highly significant; whilst there was a significant effect on increased rooting ability, this was not as great as the relative effect on shoot development. The main conclusion was that both grasses were able to tolerate the high soluble salt content of the slimes material as well as the presence of 1 980 ppm arsenic, of which at least 9 ppm could be considered available to plants, and that they could be used successfully to stabilize these mining wastes.

Keywords: arsenic; biomass; botany; conductivity; dactyloctenium geminatum; fertilizer; gatooma; grass; grasses; mining; mining waste; paspalum vaginatum; rhodesia; root growth; rooting; roots; salt; zimbabwe