The Use of Organic Amendments in the Reclamation of Acidic Coal Mine Waste

The introductory chapter presents a review of the chemical, physical and biological properties of colliery spoil, and the problems which they represent to reclamation and revegetation. The general approaches already cited in the literature for overcoming such problems are looked at as well as the varying managerial practices and after uses that are often employed. This is followed by a brief description of the field trials at Baads, Riddochhill and Loganlea and includes the rationale behind the choice of organic amendments, their suitability and supply. A number of problems resulting in poor establishment in the latter two trials are also discussed. The build-up of organic matter in the spoil is of great importance to successful reclamation as it improves the physical structure of the material and is the major source of long-term nutrient supply to any established vegetation. Chapter 3 considers the use of the most common chemical methods for the determination of organic matter and organic carbon and shows them to be unsuitable because of the high level of background carbon in the unburnt shale preventing the unambiguous measurement of the build-up of carbon from plant and microbial sources. More successful was the measurement of carbon turnover, estimated by carbon dioxide evolution. This gave comparative figures for "biological activity" and carbon turnover in spoils which received different treatments. Although the carbon turnover in the treated spoils was similar, there was considerable litter accumulation at the spoil surface which varied greatly between amendments. All the spoils showed a high level of carbon turnover, especially when compared to nitrogen and phosphorus. Chapter 4 deals with the levels, distribution and turnover of the macronutrients nitrogen, phosphorus and potassium. Nitrogen and phosphorus are particularly important as they are usually deficient in colliery spoil. Measurements of nitrogen, phosphorus and potassium in the herbage, litter and spoil were made to determine how much of a nutrient capital had been accumulated in the system, and where it was located. The ability of the spoil to supply nutrients was assessed by mineralisation experiments. Information was also obtained on nitrogen cycling by measurement of nitrification. The results of these experiments confirmed that the colliery spoil was deficient in nitrogen and phosphorus, with the exception of the chicken manure treated spoil which contained appreciable amounts of available phosphate, and that little of these nutrients was being supplied. A small fertiliser response trial was set up which showed that vegetation established on reclaimed colliery spoil responded rapidly to the supply of nitrogen, but not phosphate and potassium. A brief, concluding chapter discusses management practices in the light of the experimental results described previously