Soil water repellency (SWR) is a common phenomenon across agricultural soils of South Greenland that can negatively affect soil functions. Existing methods to measure SWR as a function of water content (w) are laborious. This study was conducted to compare the potential of visible-near-infrared spectroscopy (vis-NIRS) as an alternative method to pedotransfer functions (PTFs) for predicting four SWR indices in 143 agricultural soils from South Greenland (clay, 0.016-0.172 kg kg -1 ; organic carbon (OC), 0.009-0.241 kg kg -1 ). Pedotransfer functions were established by multiple linear regression based on OC, clay, and pH. Partial least squares regression (PLS-R) and interval PLS-R were applied to build vis-NIRS prediction models (vis-NIR range 400-2,500 nm). The area under the SWR-w curve (SWR area ) and the critical soil water content (w non ) were accurately predicted by PTFs (R 2 = .90; R 2 adj = .91) while the SWR after 60 ˚C pretreatment (SWR 60 ), and the integrative repellency dynamic index (IRDI) were predicted less accurately (R 2 adj = .36; R 2 adj = .27). Vis-NIRS models with variable selection performed at a better or close to the same level of accuracy as PTFs (SWR area , R 2 = .88; w non , R 2 = .90; SWR 60 , R 2 = .63; IRDI, R 2 = .54). This study demonstrated vis-NIRS as a valuable alternative to PTFs for rapid assessment of SWR and as a tool for SWR mitigation for farmers in South Greenland. The results may well apply to other regions with similar texture and OC ranges, but further testing is required.Abbreviations: iPLS-R, interval partial least squares regression; IRDI, integrative repellency dynamic index; LOI 550 , loss of ignition at 550 °C; MED, molarity of an ethanol droplet; MLR, multiple linear regression; OC, organic carbon; PLS-R, partial least squares regression; PTF, pedotransfer function; R 2 adj , R 2 adjusted for number of independent variables; RMSE CV , RMSE of the cross-validation; SRMSE, standardized root mean square error; SWR, soil water repellency; SWR 60 , soil water repellency after 60 °C pretreatment; SWR area , area under the SWR-w curve; vis-NIRS, visible-near-infrared spectroscopy; w, water content; w non , critical soil water content.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

The warming climate is rapidly changing the circumpolar region, presenting new opportunities and challenges for agricultural production in South Greenland. The warming climate is projected to increase the frequency of drought periods, but little is known about the soil-water retention (SWR) and the plant available water (PAW) of the agricultural soils in the region. This study aimed to measure the SWR and PAW of Greenlandic agricultural soils and evaluate the effect of organic carbon (OC) and clay (CL) content using pedotransfer functions based on OC and CL. The study included 464 South Greenlandic agricultural soil samples from 20 fields with a wide distribution in clay (0.016-0.184 kg kg −1 ) and OC contents (0.006-0.254 kg kg −1 ). Pedotransfer functions were successfully developed for estimating the gravimetric water content (w) at five soil-water potentials (−1500, −100, −30, −10, and −5 kPa) and PAW. The OC content was the primary variable governing the gravimetric water content at each soil-water potential, evidenced by R 2 values consistently above 0.80.The effect of OC on the gravimetric water content at −1500 kPa was close to the range reported in the literature, but OC effects were markedly higher between −100 and −5 kPa. Overall, this study highlights a substantial effect of OC on the PAW as a 1% increase in OC increased PAW by more than 4%, which is almost twice the value of a recent meta-study. Our study highlights the potentially dominating effects of organic matter on soil-water balance and availability in high-latitude agriculture.