PAPER-MILL BOILER ASH AND LIME BY-PRODUCTS AS SOIL LIMING MATERIALS

The pulp and paper industry in the southeastern USA produces approxima te to 6500 t of boiler ash and lime by-products (waste lime, grit, end 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 lan d-applied. Seventeen boiler ash samples and 14 Lime by-products from 1 2 Alabama pulp and paper mills were analyzed and evaluated for their p otential as soil liming materials. Most boiler ash resulted from the b urning of wood or wood in combination with other materials and average d 37% calcium carbonate equivalent (CCE), while 14 lime by-products av eraged 99% CCE. In an 84-d incubation study, boiler ash and Lime by-pr oducts applied to an acid (pH = 5.2) Marvyn loamy sand (line-loamy, si liceous, thermic, Typic Kanhapludults) at equivalent rates based on CC E resulted 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, mantmorillonitic, thermic Vertic Hapludalfs), dallis grass-fescue (Paspalum dilatatum Poir.-Festuca arundinacea Schreb.) he rbage yield increased 62% the second year and 49% the third year after surface application of boiler ash, lime by-products, and agricultural lime.