“Brown Mud” from the Aluminum Industry as a Soil Liming Material
1955
Whittaker, Colin W. | Armiger, W. H. | Chichilo, P. P. | Hoffman, W. M.
“Brown mud” is a siliceous waste product resulting from the extraction of alumina from bauxite. Present production is estimated to exceed half a million tons annually, the disposal of which is a problem in the industry. When dry, the mud contains approximately SiO₂ 23, CaO 47, Fe₂O₃ 10, TiO₂ 3.5, Al₂O₃ 5.5, and Na₂O 3.6%, and small amounts of other elements. In a greenhouse study with sweetclover as the indicator crop, using acid Evesboro and Chester soils, the dried brown mud produced yields substantially equal to those obtained with equivalent amounts of other liming materials. Emergence counts and appearance of the crop gave no indications of any toxic effects from the use of the mud. The mud increased soil pH to values that were usually equal to or exceeding those produced by finely divided agricultural limestone and were sometimes equal to those produced with hydrated lime. The calcium concentration in the dried plant material increased as the liming rate increased in about the same manner with the mud as with the other liming materials. As might be expected, the sodium content of the crop tended to be higher where the mud was used. The potassium content of the crop was reduced to a greater extent by the mud than by either hydrated lime or limestone: this effect was probably also due to the sodium content of the mud. The data indicate that the dried mud is a satisfactory liming material.
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