Water repellency prediction in high‐organic Greenlandic soils: Comparing vis–NIRS to pedotransfer functions. Issue 3 (29th April 2022)

• Record Type: Journal Article
• Authors: Blaesbjerg, Natasha H.; Weber, Peter L.; de Jonge, Lis Wollesen; Moldrup, Per; Greve, Mogens H.; Arthur, Emmanuel; Knadel, Maria; Hermansen, Cecilie
• Is Part Of: Soil Science Society of America Journal. Volume 86:Issue 3(2022)
• Page Start: 643
• Page End: 657
• Publication Date: 2022-04-29
• Subjects: Soils -- United States -- Periodicals; Soil science -- Periodicals; Periodicals; 631.4973
• DOI: 10.1002/saj2.20407
• Languages: English
• ISSNs: 0361-5995

Abstract

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 (SWRarea ) 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 (SWR60 ), 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 (SWRarea, R 2 = .88; w non, R 2 = .90; SWR60, 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. Core Ideas: Soil water repellency (SWR) vs. w curves were measured for 143 South Greenlandic soil samples. The area under the SWR– w curve and the critical w were determined. PTFs based on basic soil properties predicted SWRarea and w non accurately. Rapid spectral measurements (vis–NIRS) predicted SWR indices with similar accuracy. Variable selection within the vis–NIR spectrum (iPLS‐R) improved vis–NIRS model performance.