Andisols from Four Different Regions of Iceland

Abstract

Limited information has been published on Andisols in Iceland, but such data are important for understanding the erosional and periglacial processes that are intense in Iceland. The objectives of this research were to investigate Andisols that developed in tephra and eolian materials and that are highly susceptible to soil erosion, and to evaluate the effectiveness of the recently established Andisol order for providing meaningful classes in Iceland. Four soils that formed in 1‐ to 3‐m‐thick tephra and eolian materials of various origins were studied. The soils have low bulk density (−3), high −0.033 and −1.5 MPa water retention (0.27–1.18 and 0.17–0.85 kg kg⁻¹, respectively, excluding tephra horizons), and Atterberg limits characteristic of field‐moist Andisols (plastic limits of 0.49–0.95 kg kg⁻¹ and liquid limits of 0.54–0.97 kg kg⁻¹). Soil reaction (H₂O) ranges between pH 5.6 and 6.7. Organic C contents are high but erratic; they range from 21 to 90 g kg⁻¹, excluding thick tephra horizons that are characteristically low in C. Soil color was not related to organic C content. The cation‐exchange capacity is generally high (22–46 cmol_c kg⁻¹) and is highly related to organic C, oxalate‐extractable Al + Fe, and precipitation (R² = 0.92). The 2 of Andisols may occur in Iceland, which would constitute 5 to 6% of all Andisols in the world.