Tokuro Abe

Chemistry and fertility of acid Andisols with special reference to subsoil acidity

We examined the chemistry and fertility of Japanese Andisols in relation to clay mineralogical composition and subsoil acidity.

Phytotoxicity of monomer aluminium ions and hydroxy-aluminium polymer ions in an Andosol

Aluminium (Al) toxicity in plants occurs frequently in nonallophanic Andosols dominated by 2:1 minerals. However, the ionic species of Al causing Al toxicity in soil are still under discussion. Therefore, the phytotoxicity of monomer Al (M-Al) ions and hydroxy-Al polymer (P-Al) ions in Andosols were examined both by measuring the root growth of rice plants (Oryza saliva L. cv. Chiyohonami) under submerged soil culture, and by characterizing the adsorption reaction of M-Al ions and P-Al ions to a nonallophanic Andosol. M-Al ions were less toxic to the roots of rice plants than were P-Al ions, when compared in solution culture at Al concentrations ranging from 0–40mg L-1. The concentrations of M-Al ions and P-Al ions inhibiting root elongation of rice plants by about 50% were 11.5 mg L-1 and 4.5 mg L-1, respectively. However, the root elongation of rice plants was much more inhibited when grown in submerged soil treated with M-Al ions, than when grown in similar soil treated with P-Al ions. Aluminium concentrations for these comparisons ranged from 0–1000 mg L-1. The adsorption of P-Al ions by an Andosol was more selective than was the adsorption of M-Al ions. Our conclusions are that M-Al ions are more important in the expression of Al toxicity of plants than are P-Al ions in nonallophanic Andosols.