Nature and Liming Value of Quenched Calcium Silicate Slag

Fluorine Content of Plants

“…It would require 448 incorporations of 16 per cent superphosphate at the rate of 500 pounds per acre to introduce this amount of P205. The reason for this excessive rate was to duplicate the quantity of CaF2 introduced by a 20-ton incorporation of the calcium silicate slag (11,12) that had proved distinctly toxic. A fluoride-free concentrated superphosphate was used to supply an identical incorporation of P2Os, To obviate the certain detriment of the substantial acidity of the heavy incorporation of the soluble phosphate and to minimize any "salt effect", the soil had been prelimed with a 20-ton CaCOsequivalent incorporation of a mild liming material, the mineral calcium silicate (wollastonite).…”

“…Possible explanations have been advanced to account for the fact that distinct toxicity has been induced by the slag only in pot cultures, and then solely by heavy incorporations of 100-mesh material (12). All of the additions of liming Pots of lower row received correspondingly identical treatments except for the introduction of fluorine at the per-acre rate of 122 pounds by the calcium fluoride content of the experimental slag.…”

Siliceous Materials in Plant Nutrition, Review of the Effects of Siliceous Dressings on the Nutrient Status of Soils

“…Extensive greenhouse tests by Mac-Intire and coworkers (24,25) related the effects of a slag to its physical properties and chemical composition. Quenched low-alumina electric furnace slag was more effective than an equal w'eight of limestone of similar particle size in dressings of up to 5 tons per acre.…”

Phosphate Furnace Slag vs. Limestone, A 10-Year Lysimeter Study of Soil Liming

“…Composition, characteristics, and effectiveness of the slag as a liming material, and its attendant influence upon plant growth and composition have been reported (6,70,(72)(73)(74)(75). But where charges of unwashed brown rock phosphate or "matrix" were used in an industrial operation of the electric furnace, the resultant slag proved virtually devoid of liming value and hence enormous quantities of calcium and large amounts of included phosphorus of potential fertilizer value are locked within gigantic piles of relatively inert slag.…”

“…But where charges of unwashed brown rock phosphate or "matrix" were used in an industrial operation of the electric furnace, the resultant slag proved virtually devoid of liming value and hence enormous quantities of calcium and large amounts of included phosphorus of potential fertilizer value are locked within gigantic piles of relatively inert slag. After slag is incorporated, its silicate content undergoes hydrolysis into calcium hydroxide, which reacts with the acidoids and carbon dioxide of the soil (6). A distinctive property of the slag is that suspensions of it in carbon dioxideimpregnated water impart calcium bicarbonate concentrations far beyond those resultant from similar suspensions of calcium carbonate in any form (7,74).…”