Compression and rebound characteristics of agricultural sandy pasture soils from South Greenland

The reduction of permafrost areas and a prolonged vegetation period, both due to the ongoing climate change, open up new possibilities for agricultural activities in the circumpolar region. Presently, not much is known about the physical and functional properties of subarctic agricultural soils, making it challenging to evaluate soil impacts from increased agricultural activity. This study aims at assessing the mechanical properties of sandy Greenlandic pasture soils regarding a potential future land-use change. The compression curves of 210 undisturbed soil core samples of three pasture fields in South Greenland and, as comparison, four intensively cultivated agricultural fields in Denmark were generated by uniaxial confined compression tests (UCCT). Four soil mechanical properties were determined: the precompression stress (σ_pc) as a measure of soil strength, the compression index (C_c) as a measure of compressibility, the swelling index (C_s) as a measure of resilience to compaction and the rebound (Δε) after a relaxation time of 60 s as a measure of short-time recovery from compaction. The Greenlandic pasture soils exhibited significantly higher σ_pc than the Danish cultivated soils despite their significantly lower initial bulk density, ρ_b. The C_c negatively correlated with ρ_b, and the Greenlandic soils showed higher C_c values than the Danish soils. The C_s showed a reciprocal correlation with ρ_b and, partly due to lower ρ_b of the Greenlandic soils, higher C_s than the Danish soils. The South Greenlandic sandy pasture soils showed compression and rebound characteristics on level with Danish loamy cultivated soils, likely due to a high content of particulate organic matter (non-degraded organic matter, including grass root-mat residues).