Coal gasification slag is an ash byproduct remaining after the volatization process. This material is currently under utilized. A series of experiments were conducted to determine the suitability of coal gasification slag as a growing medium or growing medium amendment. Chrysanthemums, lettuce, poinsettias and some bedding plants were grown in slag or slag amended media in an ebb and flow fertigation system. Slag alone has a high pH and initial slag samples had some very small particle sizes. Plant growth in slag alone was poor because of high pH and low aeration. When slag was amended with moss peat, the pH was lowered to an acceptable range and the aeration was better. Plant growth in peat-slag media was equal to plant growth in a peat-perlite mix. Media composed of peat-slag and bark were also successful in producing crop growth equal to peat-perlite. There were no nutritional problems growing in slag amended media except that boron uptake by chrysanthemum was greater than in other media. Eliminating the small particle sizes by washing the slag makes the slag easier to handle, but does not produce crop growth equal to slag amended media.
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