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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,* , 2
 and 2
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 on-line soil sensor; vis-NIR spectroscopy; soil pH; lime recommendation map
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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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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