Glacial Rock Flour as Soil Amendment in Subarctic Farming in South Greenland

Abstract

Agriculture in subarctic regions is limited by a short and cold growing season. With warming in the region, the number of growing days and, consequently, the potential for agricultural intensification and expansion may increase. However, subarctic soils are typically acidic, low in plant-available nutrients, and coarsely textured, so they require soil amendment prior to intensification. This is the case in South Greenland, where we tested the use of glacial rock flour (GRF) produced by glaciers as a soil amendment. An experiment was made on a farm in South Greenland during the 2019 summer to quantify the short-term effect of applying GRF to a field dominated by perennial timothy grass. Three treatments were compared to control sites (n = 5): 20 t GRF ha−1 without conventional NPK-fertilizer, as well as 20 and 40 t GRF ha−1 in combination with 25% NPK-fertilizer. The experiment showed no significant response in biomass production (aboveground and belowground) for the plots treated with GRF only. The low rate of GRF combined with 25% NKP showed a marked and significant increase in yield in contrast to a high GRF rate with NPK, which resulted in a significant reduction in yields. The chemical composition of the plants versus soil and GRF showed that the plant uptake of nutrients was significantly higher for NPK-fertilized plots, as expected, but no differences were found between GRF-treated plots and the control plots with respect to nutrient availability or pH in the soil. We conclude that adding water and fertilizer has the potential to increase yields in South Greenland, but applying glacial rock flour as a short-term agricultural supplement needs to be further investigated before it can be recommended.

Decoupling of particles and dissolved iron downstream of Greenlandic glacier outflows

“…This Fe source is particularly relevant to fjords and coastal regions surrounding the Greenland Ice Sheet (GrIS), which discharges ~1200 Gt of freshwater annually to surrounding waters (Bamber et al, 2018). The meltwater discharged from the GrIS can contain substantial loads (>3000 mg/L) of fine-grained glacially abraded particles that are rich in Fe and other biologically relevant elements including silicon (Si) (Meire et al, 2016;Sukstorf et al, 2020). Due to unabated warming Arctic air temperatures and intensified GrIS melting, fluxes of any glacially-derived elements that scale with discharge volume are expected to increase in the future (Vizcaíno et al, 2014).…”

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

“…Regarding the slow dissolution rates of the primary silicates found in the GRF, especially in cold environments, the results of Sukstorf et al. (2020) were expected. In contrast to conventional soil amendments, for example, organic and artificial fertilizers, or liming, the addition of a fine‐grained mineral material to soil is a long‐term and profound intervention on the soil, and any negative effect on the latter needs to be assessed before large‐scale application.…”

“…Furthermore, Gunnarsen (2020) concluded that high rates of GRF application increased biomass production in active soil environments following enhanced weathering of the mineral material. Sukstorf et al (2020) presented the results of a oneseason (2 mo) field experiment in Greenland and concluded that an amendment with only GRF was not suited as shortterm fertilizer; however, a combination of GRF and artificial N-P-K fertilizer significantly increased the yields. Regarding the slow dissolution rates of the primary silicates found in the GRF, especially in cold environments, the results of Sukstorf et al (2020) were expected.…”

“…Sukstorf et al (2020) presented the results of a oneseason (2 mo) field experiment in Greenland and concluded that an amendment with only GRF was not suited as shortterm fertilizer; however, a combination of GRF and artificial N-P-K fertilizer significantly increased the yields. Regarding the slow dissolution rates of the primary silicates found in the GRF, especially in cold environments, the results of Sukstorf et al (2020) were expected. In contrast to conventional soil amendments, for example, organic and artificial fertilizers, or liming, the addition of a fine-grained mineral material to soil is a long-term and profound intervention on the soil, and any negative effect on the latter needs to be assessed before largescale application.…”

“…Sukstorf et al. (2020) presented the results of a one‐season (2 mo) field experiment in Greenland and concluded that an amendment with only GRF was not suited as short‐term fertilizer; however, a combination of GRF and artificial N–P–K fertilizer significantly increased the yields. Regarding the slow dissolution rates of the primary silicates found in the GRF, especially in cold environments, the results of Sukstorf et al.…”