Revegetation of mine wastes at Mt. Isa, Queensland. I. The nature of the material and defining the problems

Abstract

A series of chemical and physical analyses in the laboratory and field were undertaken on the fine crushed rock material disposed of after ore extraction as large flat tailings dams, The aim was to define those factors limiting plant growth. Analysis showed that available phosphorus was extremely low. Nitrogen levels were also low. pH was approximately neutral between 6.7 and 7.6, due to the high levels of dolomite. Soluble salts, particularly NaCI, MgSO4 and CaSO4 were high, leading to high values of conductivity, up to 0.052 m Sm-1. The particle size distribution was dominated by fine fractions. In the field high bulk density values up to 1.57 g cm-3 , combined with strong surface crusting lead to low values of infiltration. Thus high salt levels are not readily leached. These factors as limitations to plant growth are discussed.