The maintenance of grassland on smelter wastes in the lower Swansea Valley. III. Zinc smelter waste

  • Published source details Gemmell R.P. & Goodman G.T. (1980) The maintenance of grassland on smelter wastes in the lower Swansea Valley. III. Zinc smelter waste. Journal of Applied Ecology, 17, 461-468.


Large-scale reclamation trials, using applications of organic materials and pulverized fuel ash, combined with sowing of grasses, aimed at establishment and maintenance on zinc smelter waste were set up in the Lower Swansea Valley, Glamorgan, South Wales in 1965 and monitored until 1970.

Methods: Separate 0.1 ha areas were treated with ground limestone at 1,000 kg/ ha and amended with either 5 cm sewage sludge, 5 cm domestic refuse or not amended. Each area was sown with common bent grass Agrostis (capillaris) tenuis, red fescue Festuca rubra, or a complex grass mixture. A further area was amended with pulverized fuel ash only, added in 7.5, 15 or 22.5 cm deep layers, sown with a simple grass mixture. A selection of seed harvested from ‘zinc-tolerant’ grass populations (i.e. those growing on zinc-affected soils) were also sown.

Annual maintenance treatments investigated were annual fertilization (20% N: 10% P2 O5: 10% K2O) at 600 kg/ha, grass cutting and clearing once versus twice annually or soil sprinkling at 4 m³/ha in 1968.

Vegetation yield and species composition were assessed and soil characteristics determined.

Growth of the grasses (single species or mixtures) in most treatments declined markedly in 1968 and 1969. Annual fertilizer application failed to prevent this decline, which was attributed to the recurrence of zinc toxicity. Seeds from ‘zinc-tolerant’ populations however, showed satisfactory long-term growth on waste amended with organic materials but required annual NPK fertilization.

The most successful treatments in the long term (5-years of monitoring) were 15 and 22.5 cm coverings of pulverized fuel ash, followed by annual NPK fertilizer application. Application of a 5 cm layer of sewage sludge, or a 7.5 cm layer of pulverized fuel ash, initially resulted in a satisfactory grass cover but  this declined in the longer term.

Note: The compilation and addition of this summary was funded by the Journal of Applied Ecology (BES). If using or referring to this published study, please read and quote the original paper, this can be viewed at:

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