Sensors 2013, 13(8), 10177-10190; doi:10.3390/s130810177
Article

Potential of On-Line Visible and Near Infrared Spectroscopy for Measurement of pH for Deriving Variable Rate Lime Recommendations

1 Vocational School of Technical Sciences, Uludag University, Bursa 16059, Turkey 2 Environmental Science and Technology Department, Cranfield University, Bedfordshire, MK43 0AL, UK
* Author to whom correspondence should be addressed.
Received: 31 May 2013; in revised form: 18 July 2013 / Accepted: 31 July 2013 / Published: 8 August 2013
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in the UK 2013)
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Abstract: This 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 (R2 = 0.85, RMSEP = 0.18 and RPD = 2.52), as compared to very good accuracy obtained with the on-line measured spectra (R2 = 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.
Keywords: on-line soil sensor; vis-NIR spectroscopy; soil pH; lime recommendation map

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MDPI and ACS Style

Tekin, Y.; Kuang, B.; Mouazen, A.M. Potential of On-Line Visible and Near Infrared Spectroscopy for Measurement of pH for Deriving Variable Rate Lime Recommendations. Sensors 2013, 13, 10177-10190.

AMA Style

Tekin Y, Kuang B, Mouazen AM. Potential of On-Line Visible and Near Infrared Spectroscopy for Measurement of pH for Deriving Variable Rate Lime Recommendations. Sensors. 2013; 13(8):10177-10190.

Chicago/Turabian Style

Tekin, Yücel; Kuang, Boyan; Mouazen, Abdul M. 2013. "Potential of On-Line Visible and Near Infrared Spectroscopy for Measurement of pH for Deriving Variable Rate Lime Recommendations." Sensors 13, no. 8: 10177-10190.

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