Paper Mill Boiler Ash and Lime By-Products as Soil Liming Materials
- John K. Muse and
- Charles C. Mitchell*
The pulp and paper industry in the southeastern USA produces ≈ 6500 t of boiler ash and lime by-products (waste lime, grit, and dregs) daily. A survey of 88 pulp and paper mills indicated that most of these by-products are placed in landfills, with only 10% being land-applied. Seventeen boiler ash samples and 14 lime by-products from 12 Alabama pulp and paper mills were analyzed and evaluated for their potential as soil liming materials. Most boiler ash resulted from the burning of wood or wood in combination with other materials and averaged 37% calcium carbonate equivalent (CCE), while 14 lime by-products averaged 99% CCE. In an 84-d incubation study, boiler ash and lime by-products applied to an acid (pH = 5.2) Marvyn loamy sand (fine-loamy, siliceous, thermic, Typic Kanhapludults) at equivalent rates based on CCE resuited in mean pH values significantly higher than values achieved with agricultural lime. All materials increased Mehlich-1 extractable P, K, and Mg. In a field study conducted on an acid (pH = 5.1) Vaiden clay (very-fine, montmorillonitic, thermic Vertic Hapludalfs), dallisgrass-fescue (Paspalum dilatatum Poir.-Festuca arundinacea Schreb.) herbage yield increased 62% the second year and 49% the third year after surface application of boiler ash, lime by-products, and agricultural lime.
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