Short-term effects of Greenlandic glacial rock flour on soil physical properties and maize yield

Greenlandic glacial rock flour (GRF) serves as a valuable source of silicate minerals for CO₂ uptake through enhanced weathering. Additionally, its physico-chemical properties may influence soil hydro-physical characteristics and may also have a separate effect on crop yields. This study evaluated the effects of GRF application at 50 and 100 t/ha, along with an unamended control, on soil water content at field capacity (FC), plant-available water (PAW), saturated hydraulic conductivity (K_sat), and dry aggregate stability (DAS) over 120 days. Separately, maize dry matter yield (DMY) was assessed after 40 days of growth. The experiment was conducted across four soil textures, comprising coarse-textured soils (sand and sandy loam) and fine-textured soils (sandy clay loam and clay). The 100 t/ha application had the most significant (p < 0.05) impact on soil properties and maize yield, while the 50 t/ha rate showed intermediate but inconsistent effects. In fine-textured soils, the 100 t/ha treatment increased FC by 15% and PAW by 27% compared to the control, whereas in coarse-textured soils, FC and PAW rose by 29% and 26%, respectively. However, Ksat decreased by 47% in fine-textured soils and 34% in coarse-textured soils compared to the control. Maize DMY for the 100 t/ha rate increased by 18% in coarse-textured soils and 38% in fine-textured soils relative to the control. These findings suggest that GRF amendment improved hydro-physical properties more in coarse-textured soils but increased yield more in fine-textured soils, and may serve as a useful co-benefit of enhanced rock weathering.