The reclamation of acidic colliery spoil. III. Problems associated with the use of high rates of limestone

Published source details Costigan P.A., Bradshaw A.D. & Gemmell R.P. (1982) The reclamation of acidic colliery spoil. III. Problems associated with the use of high rates of limestone. Journal of Applied Ecology, 19, 193-201.
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Summary

When reclaiming acidic pyritic colliery spoil, in order to neutralize acidity generated by iron pyrites oxidation, incorporation of ground limestone is required. However, growth of white clover Trifolium repens has been shown to be inhibited by large applications of agricultural ground limestone. This may pose difficulties in establishment and maintenance of grass swards as these spoils contains no plant-available nitrogen so there is often a reliance on nitrogen fixation by leguminous herbs, e.g. clovers, to counter this problem. It is also possible that the inhibitory factors involved may restrict soil nitrification processes. In this study the effects of high rates of ground limestone incorporation on T.repens and perennial rye-grass Lolium perenne growth were compared, the influence of phosphorus availability was assessed and other possible causes of liming inhibition were investigated.

L.perenne and T.repens were sown in 14 cm diameter plastic plant pots at 200 kg/ha (equivalent rate) in monoculture in three soil substrates into which ground calcitic limestone had been added at 0, 1, 5, 12.5, 25 or 100 t/ha. Phosphorus was applied at 109 and 218 kg P/ha (as superphosphate).

The soil substrates were: acidic colliery spoil (pH 2.5) from Welch Whittle, Lancashire (National Grid reference SD 545135), northwest England; a mix (3:1 v/v) of acidic peat and silica sand (compost); and acidic silica sand. The experiment (randomized factorial) had three replicates. All the treatments received 125 kg N/ha (as ammonium nitrate) and 52 kg K/ha (as potassium sulphate) and pots, placed in a glasshouse, were watered with deionized water as required. Shoot dry matter production was determined after 11 weeks.

Effect of limestone addition: L. perenne was unaffected by ground calcitic limestone addition at rates up to 100 t/ha. It grew well in all three substrates when sufficient limestone was applied; in spoil, 5 t limestone/ha was required and in compost there was severe inhibition without limestone addition. Dry weight production was significantly lower in spoil than in the other materials, even with limestone addition.

T.repens responded similarly at low limestone addition levels but very differently when an excess of limestone was applied. On colliery spoil, more than 5 t limestone/ha suppressed growth by more than 90%. This effect was slightly less marked on compost but substantially less so (50%) on sand.

Effect of phosphorous addition: There was no pattern of L.perenne response to increased phosphorus fertilizer addition , but there was some stimulation of T.repens growth.

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: http://links.jstor.org/sici?sici=0021-8901%28198204%2919%3A1%3C193%3ATROACS%3E2.0.CO%3B2-2