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

Abstract

AbstractGreenlandic 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.