Research Summary:
Various kinds of soils can be formed from volcanic ash, depending on the specific set of soil-forming factors at different sites. Among these soils, Andisols or Andosols exhibit unique properties, largely due to the abundance of noncrystalline materials such as allophane, imogolite, Al-humus complexes, and ferrihydrite. These materials create highly porous structures in Andisols, resulting in a light and fluffy nature that can accommodate large amounts of both plant-available and hygroscopic water. These soils also possess many other physical properties that differ from those of other soils.
In addition to their physical characteristics, Andisols have unique chemical properties. These include an aluminum-rich elemental composition, significant humus accumulation in A horizons, variable charge characteristics, high phosphate retention capacity, and a high affinity for multi-valent cations. Nonallophanic Andisols, in particular, exhibit high KCl-extractable and water-soluble aluminum in an acidic to weakly acidic pH range.
Furthermore, the biological activity in volcanic ash soils is notable. Topics of interest include the phosphorus (P) supply from apatite and the potassium (K) supply from biotite for crops in fresh volcanic ash. Additionally, the effects of KCl-extractable and water-soluble aluminum on soil-borne diseases, the adsorption characteristics of viruses on Andisols, and the phosphorus tropistic root growth of Brassica plants in P-deficient Andisols are important areas of study.
Key words: Andisol, Andosol, elemental composition, noncrystalline material.
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