Nutrient deficiencies and the aftercare of reclaimed derelict land
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Published source details
Bloomfield H.E., Handley J.F. & Bradshaw A.D. (1982) Nutrient deficiencies and the aftercare of reclaimed derelict land. Journal of Applied Ecology, 19, 151-158.
Published source details Bloomfield H.E., Handley J.F. & Bradshaw A.D. (1982) Nutrient deficiencies and the aftercare of reclaimed derelict land. Journal of Applied Ecology, 19, 151-158.
Summary
When attempting revegetation of colliery spoils, there is likely to be a shortage of available nitrogen and phosphorus for plant growth. These deficiencies may not be relieved by applications of fertilizer. Also, in certain materials, particularly coal shales and metalliferous mine wastes, pyrite (FeS), is a common constituent (up to 5%), and upon oxidation substantial acidity is released. This can be countered by heavy limestone application (up to 50 tonnes/ha), but usually substantial residues of unoxidized pyrite remain with further acidity release after reclamation which can cause degeneration or death of established plants. In this study, fertilizer and limestone addition trials were carried out on 14 grass swards, eight had been established between 1 and 7 years previously, by standard methods on colliery shale, and on urban demolition wastes.
Study sites: A series of field trials were set up on 14 reclaimed sites on colliery shales and urban waste in the South Lancashire coalfield and the city of Liverpool (Merseyside), northwest England. The sites within these two groups were rather different in their parent materials and hence reclamation treatments, but were chosen as typical and illustrative of present reclamation practices.
Fertilizer addition: In May 1972, nil or 50 kg/ha N, P205, and K (21.8 kg P, 41.5 kg K) as ammonium nitrate, superphosphate and potassium sulphate were applied to 1 m² plots in factorial combination, with three replicates of each.
Liming: On the colliery shale the effect of lime was also tested by an addition of 2 tonnes/kg/ha ground limestone in a split plot arrangement. Some sites were treated again in 1973. Plant percentage cover estimates and dry weight yields (measured by a single cut on half of each plot) were made in early autumn.
Fertilizer addition: Due to variability in site characteristics and age since reclamation results were variable but some trends were evident. On colliery spoil sites (except one already with good vegetation cover) fertilizer treatments significantly increased cover, and (again except in one) had a very significant (positive) effect on yield. There was a deficiency in nitrogen (and to a lesser extent phosphorus) on the colliery spoil a year after fertilizer addition. Considerable nitrogen deficiency was also found on two urban sites where topsoil had been added in the reclamation process.
Liming: Some of the colliery spoil sites had become very acid due to continued oxidation of pyrite, but surface limestone treatments failed to penetrate the spoil at the surface. This lime addition had no effect on vegetation cover or yields.
Consclusions: From the results of this study, the authors concluded that aftercare for several years, must be an integral part of such reclamation programmes. Adequate limestone must be added during initial reclamation to counter acidification. Fertilizer applications need to be regularly repeated and there is an evident role for legumes (nitrogen-fixers) to assist in nutrient build-up.
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