Optimization of spectral pre-processing for estimating soil condition on small farms

Singh Kanika, Aitkenhead Matt, Fidelis Chris, Yinil David, Sanderson Todd, Snoeck Didier, Field Damien. 2022. Optimization of spectral pre-processing for estimating soil condition on small farms. Soil Use and Management, 38 (1) : 150-163.

Résumé : The concepts of soil security (especially relating to soil condition) provide a useful framework in building spectral libraries. Spectral libraries can be used with the purpose of assessing soil condition by measuring soil organic carbon (SOC) or increasing productivity through soil nutrient management. A spectral library was generated by measuring SOC and nutrients (nitrogen, phosphorous and potassium) and spectral reflectance data over the visible to near-infrared range (350–2,500 nm) in soil samples collected from four production systems in Papua New Guinea (PNG). The spectral library was analysed using SpecOptim, a software tool developed at the James Hutton Institute to explore spectral pre-processing and calibration options. From 192 model combinations of model, the best one was identified for each study area. Different combinations of data were also explored (e.g. by farm or all together). We believe that at the local-scale, soil carbon and nitrogen variability can be captured; however, the spectrally inactive properties such as phosphorous and potassium need to have a higher variability and therefore pooling is required in order to predict properties chemometrically. The SpecOptim software is a useful tool where analysis of spectral data can be difficult to determine. Specifically, it helped improve the accuracy of predictions by 2% for C and N (except for East New Britain site) compared with previously used pre-processing techniques and calibration models while automating identification of the optimal pre-processing approach. We believe that we have developed research-based evidence for using spectral libraries to fit with the soil priority areas of PNG.

Mots-clés Agrovoc : petite exploitation agricole, fertilité du sol, potassium

Mots-clés géographiques Agrovoc : Papouasie-Nouvelle-Guinée

Mots-clés libres : Chemometrics, Soil conditions, Spectral software, Tropical soils

Agences de financement hors UE : Australian Centre for International Agricultural Research

Auteurs et affiliations

• Singh Kanika, University of Sydney (AUS) - auteur correspondant
• Aitkenhead Matt, James Hutton Institute (GBR)
• Fidelis Chris, Cocoa Board of Papua New Guinea (PNG)
• Yinil David, Cocoa Board of Papua New Guinea (PNG)
• Sanderson Todd, CSIRO (AUS)
• Snoeck Didier, CIRAD-PERSYST-UPR Systèmes de pérennes (FRA)
• Field Damien, University of Sydney (AUS)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/605018/)

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