Physical characterization of glacial rock flours from fjord deposits in South Greenland–Toward soil amendment

Abstract

Greenlandic fjords contain vast amounts of glacially derived mineral material (glacial rock flour [GRF]), which may be used to amend structureless, low-clay, and water-repellent agricultural soils in South Greenland and elsewhere. In this study, we investigate key physical amendment properties of GRF from 16 different deposits in South Greenland. The clay-sized fraction varied largely (range, 0.11–0.57 kg kg−1), and the particles were mostly angular. The specific surface area (SSA) determined by either ethylene glycol monomethyl ether (EGME, polar liquid) (range, 13.32–88.06 m2 g−1) or water-vapor adsorption (range, 10.62–63.82 m2 g−1) agreed well (r =.90) and were comparable to kaolinitic-clay dominated cultivated soils (KA-soils) with clay content similar to the GRFs. The cation exchange capacities (CECs) (range, 4.25–21.91 cmol kg−1) were similar to or higher than those of the KA-soils. The water content at the permanent wilting point (PWP) for the GRFs were considerably lower than those of the KA-soils. The addition of 5% GRF to a sandy soil from Greenland showed a tendency (although not statistically significant) to increase plant available water (PAW). However, very high GRF addition (10 and 15%) significantly decreased the PAW. The specific surface charge (CEC/SSA) of the GRFs were higher than for comparable KA-soils, suggesting a good soil amendment potential. The results from this study are valuable toward designing sustainable GRF amendment strategies, matching a given cultivated soil with the right amount and type of GRF.