Restoration of Grassland After Magnesian Limestone Quarrying

Abstract

(1) The chemical and physical properties of Magnesian Limestone waste strongly suggested that successful restoration to grassland would require large additions of nutrients, and also organic matter to improve its texture. (2) Greenhouse experiments and field trials with commercially available seeds mixtures and amendments such as fertilizer, softwood bark, peat, topsoil and sewage sludge indicated that a combination of complete (NPK) fertilizer and an organic material are likely to be the most effective in giving satisfactory establishment and sustained growth. There was a linear relationship between growth and fertilizer, suggesting that very heavy fertilizer applications (up to 2000 kg ha-' of a balanced complete NPK formulation) could be most effective. Treated sewage sludge (at 38 t ha-') with added potassium was shown to be an alternative, being more effective than complete fertilizer at 900 kg ha-'. (3) Legumes, considered to be important because of their nitrogen accumulation potential, were found to respond markedly to complete fertilizer (at 600 kg ha-') but not to inoculation. Growth in the absence of fertilizer was negligible. (4) A comparison of different species both in pure stands and in mixtures indicated that Agrostis stolonifera L., Festuca rubra Gaud., Dactylis glomerata L., and the legumes Lotus corniculatus L. and Trifolium repens L. were likely to be the most effective in long-term reclamation. (5) These findings were confirmed in an 11-year trial, showing that permanent low maintenance grassland can be established on Magnesian Limestone wastes without recourse to deep top soil coverings.