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4591817 
Book/Book Chapter 
Primary results on on-line measurement of some selected soil properties using a VIS-NIR sensor 
Mouazen, AM; Malaki, MR; De Baerdemaeker, J; Ramon, H 
2006 
Advances in Geoecology 
38 
215-+ 
WOS:000242339000027 
The on-line measurement of soil properties is essential for site specific application of different inputs into agricultural soils. This paper reports primary results on on-line measurement of total carbon (C-tot), moisture content (MC), pH and available phosphorous (P-avl) using a soil sensor developed for on-line measurement of soil properties. The sensor consisted of a soil penetration unit (subsoiler), to which the optical unit to acquire spectra from the bottom of the trench opened by the subsoiler is attached. A mobile, fibre-type, visible (VIS) and near infrared (NIR) spectrophotometer (Zeiss Corona 45 visnir fibre) with a measurement range of 306.5 - 1710.9 nm was used to measure soil spectra in reflectance mode. Global calibration models were established under non-mobile laboratory environment, considering samples collected from large areas covering Belgium and northern France. These models were developed using the partial least squares (PLS) regression analysis coupled with the leave one-out cross-validation technique. On the basis of the values of determination coefficient (R) and the ratio of standard deviation of calibration set (SD) to root mean square error of cross validation (RMSECV), the prediction of MC was evaluated as good, whereas the predictions of C-tot, pH and P-avl were evaluated as only possible to provide quantitative approximations. When these models were used for on-line measurement, they provided moderate similarity of maps between on-line and reference measurement methods. Mean error values of 5.97%, 0.37%, 5.10% and 27.48% were found between the on-line and reference measurements of C-tot, MC, pH and P-avl, respectively, suggesting the potential use of the VIS-NIR sensing system for on-line measurement of soil properties. 
soil properties; on-line sensor; visible; near infrared; spectroscopy; maps