Glacial rock flour reduces the hydrophobicity of Greenlandic cultivated soils

Abstract

Soil water repellency (WR) is ubiquitous across Greenlandic cultivated fields, which may constrain agricultural production. Fine-grained glacial rock flour (GRF) is available in the surrounding landscape, which could serve as a soil amendment. We tested whether the application of GRF (rates of 0, 50, 100, 300, and 500 ton ha −1 ) reduced the WR across two field trials in South Greenland. The field trials, Upernaviarsuk (UP) and South Igaliku (SI), differed in clay (UP: 0.05-0.11 kg kg −1 ; SI: 0.03-0.05 kg kg −1 ) and organic carbon (OC) contents (UP: 0.04-0.13 kg kg −1 ; SI: 0.01-0.03 kg kg −1 ). We measured WR across gravimetric water contents (W) from oven-dry to the W where WR ceased (W NON ) to obtain whole WR-W curves. Most soils became hydrophilic around air-dry conditions at application rates of ≥300 ton ha −1 , likely due to increased clay:OC ratios. Application rates of ≥300 ton ha −1 generally reduced the trapezoidal integrated area of the WR-W curve (WR AREA ), W NON, and WR after heat treatments at 105˚C (WR 105 ) and 60˚C (WR 60 ). The WR 105 was significantly reduced in both fields at 500 ton ha −1 , while WR 60 was significantly reduced in UP at application rates of ≥300 ton ha −1 . The GRF effects were masked by texture and OC variations. Normalizing WR AREA to the water vapor sorption isotherms (utilizing the Campbell-Shiozawa model) revealed that GRF consistently reduced the normalized WR AREA . The SI field showed the largest reduction in the normalized WR AREA , likely due to its lower OC and clay contents. Thus, GRF could reduce WR across two Greenlandic field trials.

Soil carbon determination for long‐term monitoring revisited using thermo‐gravimetric analysis

“…The value of 0.55 for temperate soils lies midway between that for cellulose and lignin, perhaps suggesting the temperate Great Britain soil OM is a balance of similar materials. In comparison, Arctic soils with lots of fresh plant material and low decomposition rates have been found to have a slope of 0.46 (Weber, 2022). Conversely, as organic material is compressed and turns to coal, values as high as ∼0.89 are reported for anthracite.…”