A root growth study used to examine the suitability of two grasses for stabilizing toxic mine wastes¹

Part of a thesis approved for the M.Phil, degree, University of Rhodesia.

Abstract

The rooting ability of Dactyloctenium geminatum 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. geminatum. 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 8 ppm could be considered available to plants, and that they could be used successfully to stabilize these mining wastes.

Uittreksel

‘n Studie van die wortelgroeivermoë van Dactyloctenium geminatum en Paspalum vaginatum was gemaak in ‘n pot‐proefwaarin mynslyk gebruik was, wat ‘n totaal van 1 980 d.p.m. arseen bevat, en ‘n soortlike geleidingsvermoë van 16 050 mikromhos het. In die potproef het P. vaginatum ‘n biomassa van tenminste dubbel die wortels en lote opgelewer in vergelyking met D. geminatum. Die uitwerking van ‘n toediening van ‘n kunsmis mengsel (8N: 15P: 10K) teen 1 000 kg per hektaar op lootonwikkeling was hoogs betekenisvol en terselfdertyd was daar ‘n betekenisvolle vermeerdering van die wortelgroei vermoë, al was die relatiewe uitwerking egter nie so groot as op die ontwikkeling van lote nie.

Die hoof gevolgtrekking was dat albei grasse die vermoë het om die hoë soutinhoud sowel as die teenwoordigheid van 1 980 dp.m. arseen, waarvan tenminste 8 d.p.m. beskikbaar was vir opname deur die plante, te weerstaan, endat albei met sukses gebruik kan word om hierdie vergifte slykmateriaal in mynhope te stabiliseer.

Notes

Part of a thesis approved for the M.Phil, degree, University of Rhodesia.