Extraction of active aluminum from acid soils in Japan with different reagents

The paper deals with methods of determining active aluminum in acid soils. Extraction reagents examined were 4 acids, 4 salts, and 11 compounds of chelating agents. The effects of different conditions, such as pH, temperature, shaking time and the ratio of solution to soil were observed. Barium salicylate solutions, in which the normal concentration of barium and the molar concentration of salicylate were 1.0 and 0.1 respectively, were found promising as extractants. Initial pH of the solution, shaking time and the ratio of solution to soil were set at 7.0, 2 hours and 50:1, respectively. Ammonium salicylate and ammonium EDTA also extracted active aluminum but amounts varied according to different conditions. The most promising procedure was applied to a few kinds of soils and to soil treated with either lime or phosphate. The amounts of aluminum extracted from soils high in humus were larger than those from soils low in humus. Liming or phosphate application decreased the amounts of aluminum extracted.