Gas diffusion characteristics of agricultural soils from South Greenland

Abstract

The Arctic is warming at twice the global average, which may impact agricultural production in Greenland. Therefore knowledge of the functional properties of Greenlandic soil resources is necessary. The relative soil gas diffusivity [the soil gas diffusion coefficient (D p)-free-air diffusion coefficient (D o) ratio] is the chief parameter controlling gas transport in soils. Predictions of D p /D o are needed to estimate root zone aeration and terrestrial greenhouse gas fluxes. We used existing models to analyze the D p /D o of soils from Greenlandic fields and a pore connectivity index (C ip) to infer their degree of structural development and identify the main parameters controlling D p /D o. In total, 201 × 3 intact 100-cm 3 soil samples were sampled across six fields with clay and organic C contents of 0.016 to 0.089 and 0.016 to 0.105 kg kg −1 , respectively. The D p /D o was measured with the one-chamber nonsteady-state method at soil water potentials between-10 and-1,000 cm H 2 O. Accurate determination of total porosity (Φ) was ensured by calibrating a particle density model on 129 samples. The soils exhibited a less developed structure and highly tortuous pore networks, resulting in low D p /D o as a function of air-filled porosity (ε). Density-corrected models with air saturation (ε/Φ) reduced the RMSE. Furthermore, C ip at-1,000 cm H 2 O soil water potential increased linearly with dry bulk density (ρ b), suggesting that ρ b is a key controller of D p /D o , which is important for planning cultivation practices for Southern Greenlandic soils. Lastly, we found that an air saturation >35% is required for adequate soil aeration. Abbreviations: CF, coarse fraction; C ip , pore connectivity index; D o , diffusion coefficient of oxygen in free air; D p , oxygen soil gas diffusion coefficient; D p /D o , relative soil gas diffusivity; GDC, generalized density-corrected model;

Soil–air phase characteristics: Response to texture, density, and land use in Greenland and Denmark

“…The sensitivity of ε to changes in ρ b of the arctic pasture soils was generally lower (Figure 7c) compared to the temperate cultivated soils, although the low Ω-values pointed toward a lack of soil structure. Weber et al (2020) investigated the pore-network connectivity of the herein presented arctic pasture soils and concluded that the pasture soils showed only little to no soil-structure development, which is in accordance with the low Ω-values found in this study.…”

“…The Greenlandic sites are described in Weber et al (2020) and Pesch et al (2020). In total, 396 individual soil core samples from five pasture fields from south-west Greenland were included in this study (132 individual sampling points, three replicates per point).…”

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

“…The South Greenlandic soils are characterized by a relatively coarse texture and moderate to high organic matter (OM) content and show little to moderate soil development (Jakobsen, 1991); Caviezel et al, 2017;Weber et al, 2020;Pesch et al, 2021). In a recent study, Weber et al (2021) revealed the hydrophobic tendency of Greenlandic agricultural soils, which was attributed to the combination of coarse soil texture and high OM content.…”

“…In a recent study, Weber et al (2021) revealed the hydrophobic tendency of Greenlandic agricultural soils, which was attributed to the combination of coarse soil texture and high OM content. Furthermore, Pesch et al (2021) revealed the quasi absence of any soil aggregation and Weber et al (2020) pointed out the complexity of adequate soil aeration because of pronounced pore network tortuosity. The cold environment, relatively coarse soil texture, and the lack of soil development result in large amounts of noncomplexed OM (Pesch et al, 2020), which will be prone to degradation following increasing temperatures (Kirschbaum, 1995) or changes in soil management (Besnard et al, 1996).…”

“…The South Greenlandic soils are characterized by a relatively coarse texture and moderate to high organic matter (OM) content and show little to moderate soil development (Jakobsen, 1991); Caviezel et al., 2017; Weber et al., 2020; Pesch et al., 2021). In a recent study, Weber et al.…”