Effects of fertilizer addition to serpentine asbestos mine wastes on perennial rye-grass Lolium perenne growth; a laboratory experiment, McGill University (Montreal), Quebec, Canada
Published source details
Moore T.R. & Zimmermann R.C. (1977) Establishment of vegetation on serpentine asbestos mine wastes, southeastern Quebec, Canada. Journal of Applied Ecology, 14, 589-599
Published source details Moore T.R. & Zimmermann R.C. (1977) Establishment of vegetation on serpentine asbestos mine wastes, southeastern Quebec, Canada. Journal of Applied Ecology, 14, 589-599
In the mid 1970s, arge areas (total of 5.5 km²) of asbestos mine wastes were present in south-eastern Quebec (Canada). The areas are mainly devoid of vegetation (despite some being up to 60 years old) and are a potential health hazard. It was therefore desirable to develop techniques to produce a sustained plant cover. Laboratory and field experiments were performed to detect the factors inhibiting plant growth and to determine the levels of amendments necessary to sustain plant growth. The findings of the laboratory experiments are summarised here.
Tailing chemical characteristics: Twenty-three samples from the various mines in Quebec were analysed. The tailings have a high pH (alkaline), very low macro-nutrient (NPK) content, low Ca:Mg and K: Mg ratios, relatively large amounts of Ni and Cr and a low available water capacity.
Laboratory experiments: Perennial rye-grass Lolium perenne was grown on tailings in pot trials. Ammonium nitrate, sodium phosphate, potassium sulphate, and calcium carbonate were applied at rates equivalent to 1 kg fertilizer/m², both individually and in combined treatments. The experiment was run in a glasshouse for 6 weeks.
Ca, P and K applications increased L.perenne leaf growth whilst N application did not; this apparent anomaly may have been due to N-fixation by algae, which appeared on many of the fertilized pots. The addition of the very soluble fertilizers, e.g. potassium sulphate and ammonium nitrate, tended to delay germination, presumably through low soil water potentials created by high solute concentrations. The effects of solute concentration and Ca:Mg ratio on germination were investigated further:
L.perenne seeds were placed on filter paper in Petri dishes and wetted with solutions of various concentrations of Ca and Mg chlorides and various Ca:Mg ratios. Germination decreased as concentrations increased (between 0.01 and 0.1 M). The Ca:Mg ratio only affected germination at the highest concentration of 0.1 M; germination rates at Ca:Mg ratios of 1:25 or 1:50 were half those at 1:5, 1:1 or 5:1. Such high solute concentrations (0.1 M) might occur in the field where evaporative drying has occurred, where acidification has been used as a remediation technique to counter alkalinity, or where large quantities of soluble fertilizers have been applied.