Kuang, BoyanMouazen, Abdul M.2022-11-172022-11-172013-07-31Tekin, Y. vd. (2013). "Potential of on-line visible and near infrared spectroscopy for measurement of pH for deriving variable rate lime recommendations". Sensors, 13(8), 10177-10190.1424-8220https://doi.org/10.3390/s130810177https://www.mdpi.com/1424-8220/13/8/10177http://hdl.handle.net/11452/29470This paper aims at exploring the potential of visible and near infrared (vis-NIR) spectroscopy for on-line measurement of soil pH, with the intention to produce variable rate lime recommendation maps. An on-line vis-NIR soil sensor set up to a frame was used in this study. Lime application maps, based on pH predicted by vis-NIR techniques, were compared with maps based on traditional lab-measured pH. The validation of the calibration model using off-line spectra provided excellent prediction accuracy of pH (R-2 = 0.85, RMSEP = 0.18 and RPD = 2.52), as compared to very good accuracy obtained with the on-line measured spectra (R-2 = 0.81, RMSEP = 0.20 and RPD = 2.14). On-line predicted pH of all points (e.g., 2,160) resulted in the largest overall field virtual lime requirement (1.404 t), as compared to those obtained with 16 validation points off-line prediction (0.28 t), on-line prediction (0.14 t) and laboratory reference measurement (0.48 t). The conclusion is that the vis-NIR spectroscopy can be successfully used for the prediction of soil pH and for deriving lime recommendations. The advantage of the on-line sensor over sampling with limited number of samples is that more detailed information about pH can be obtained, which is the reason for a higher but precise calculated lime recommendation rate.eninfo:eu-repo/semantics/openAccessChemistryEngineeringInstruments & ınstrumentationOn-line soil sensorVis-NIR spectroscopySoil pHLime recommendation mapSoilSensorCalibrationForecastingLimeNear infrared spectroscopySocial networking (online)SoilsOn-line measurementPrediction accuracyReference measurementsSoil sensorsVis-NIR spectroscopyVisible and near infraredVisible and near-infrared spectroscopyInfrared devicesArticle0003286248000322-s2.0-84923026051101771019013823966186Chemistry, analyticalEngineering, electrical & electronicInstruments & instrumentationSoil Color; Near-Infrared Spectroscopy; Hyperspectral