Water repellency prediction in high‐organic Greenlandic soils: Comparing vis–NIRS to pedotransfer functions

• Published in: Soil Science Society of America Journal
• Main Authors: Blaesbjerg, Natasha H., Weber, Peter L., de Jonge, Lis Wollesen, Moldrup, Per, Greve, Mogens H., Arthur, Emmanuel, Knadel, Maria, Hermansen, Cecilie
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2022
• Subjects: Greenland; greenlandic
• Online Access: http://dx.doi.org/10.1002/saj2.20407; https://onlinelibrary.wiley.com/doi/pdf/10.1002/saj2.20407; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/saj2.20407

Abstract 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.