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Online measurement of soil organic carbon as correlated with wheat normalised difference vegetation index in a vertisol field.

Tekin Y, Ulusoy Y, Tümsavaş Z, Mouazen AM - ScientificWorldJournal (2014)

Bottom Line: Calibration model of SOC in full cross-validation resulted in a good accuracy (R (2) = 0.75, root mean squares error of prediction (RMSEP) = 0.17%, and ratio of prediction deviation (RPD) = 1.81).The validation of the calibration model using laboratory spectra provided comparatively better prediction accuracy (R (2) = 0.70, RMSEP = 0.15%, and RPD = 1.78), as compared to the online measured spectra (R (2) = 0.60, RMSEP = 0.20%, and RPD = 1.41).Although visual similarity was clear, low similarity indicated by a low Kappa value of 0.259 was observed between the online vis-NIR predicted full-point (based on all points measured in the field, e.g., 6486 points) map of SOC and NDVI map.

View Article: PubMed Central - PubMed

Affiliation: Vocational School of Technical Science, Uludag University, 16059 Bursa, Turkey.

ABSTRACT
This study explores the potential of visible and near infrared (vis-NIR) spectroscopy for online measurement of soil organic carbon (SOC). It also attempts to explore correlations and similarities between the spatial distribution of SOC and normalized differential vegetation index (NDVI) of a wheat crop. The online measurement was carried out in a clay vertisol field covering 10 ha of area in Karacabey, Bursa, Turkey. Kappa statistics were carried out between different SOC and NDVI data to investigate potential similarities. Calibration model of SOC in full cross-validation resulted in a good accuracy (R (2) = 0.75, root mean squares error of prediction (RMSEP) = 0.17%, and ratio of prediction deviation (RPD) = 1.81). The validation of the calibration model using laboratory spectra provided comparatively better prediction accuracy (R (2) = 0.70, RMSEP = 0.15%, and RPD = 1.78), as compared to the online measured spectra (R (2) = 0.60, RMSEP = 0.20%, and RPD = 1.41). Although visual similarity was clear, low similarity indicated by a low Kappa value of 0.259 was observed between the online vis-NIR predicted full-point (based on all points measured in the field, e.g., 6486 points) map of SOC and NDVI map.

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Related in: MedlinePlus

Q-Q plots between laboratory measured versus laboratory visible and near infrared (vis-NIR) predicted (a) and laboratory measured versus online vis-NIR predicted (b) soil organic carbon (SOC). The two plots were based on 25 samples of the validation set.
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fig7: Q-Q plots between laboratory measured versus laboratory visible and near infrared (vis-NIR) predicted (a) and laboratory measured versus online vis-NIR predicted (b) soil organic carbon (SOC). The two plots were based on 25 samples of the validation set.

Mentions: General Q-Q plot was used to assess the visual similarity of the distributions of datasets (Figure 7). Q-Q plots compare the quintiles of data distribution with the quintiles of standardized theoretical distribution from a specified family of distributions [44]. Q-Q plots for laboratory measured SOC versus laboratory vis-NIR predicted SOC (Figure 7(a)) based on 25 samples of the validation set show normal distribution of the datasets, indicating high similarity between the two maps. However, in Q-Q plot for laboratory measured SOC versus online vis-NIR predicted SOC (Figure 7(b)), there are two points, one at 1.65% and the other at 1.21% SOC. Both the points are vertically separated from the rest of the 25 points, indicating a deterioration of similarity with the online predicted map, caused by the ambient conditions and/or the error attributed to the mismatch of sample position and corresponding spectra of the 25 samples collected for validation during the online measurement.


Online measurement of soil organic carbon as correlated with wheat normalised difference vegetation index in a vertisol field.

Tekin Y, Ulusoy Y, Tümsavaş Z, Mouazen AM - ScientificWorldJournal (2014)

Q-Q plots between laboratory measured versus laboratory visible and near infrared (vis-NIR) predicted (a) and laboratory measured versus online vis-NIR predicted (b) soil organic carbon (SOC). The two plots were based on 25 samples of the validation set.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4109388&req=5

fig7: Q-Q plots between laboratory measured versus laboratory visible and near infrared (vis-NIR) predicted (a) and laboratory measured versus online vis-NIR predicted (b) soil organic carbon (SOC). The two plots were based on 25 samples of the validation set.
Mentions: General Q-Q plot was used to assess the visual similarity of the distributions of datasets (Figure 7). Q-Q plots compare the quintiles of data distribution with the quintiles of standardized theoretical distribution from a specified family of distributions [44]. Q-Q plots for laboratory measured SOC versus laboratory vis-NIR predicted SOC (Figure 7(a)) based on 25 samples of the validation set show normal distribution of the datasets, indicating high similarity between the two maps. However, in Q-Q plot for laboratory measured SOC versus online vis-NIR predicted SOC (Figure 7(b)), there are two points, one at 1.65% and the other at 1.21% SOC. Both the points are vertically separated from the rest of the 25 points, indicating a deterioration of similarity with the online predicted map, caused by the ambient conditions and/or the error attributed to the mismatch of sample position and corresponding spectra of the 25 samples collected for validation during the online measurement.

Bottom Line: Calibration model of SOC in full cross-validation resulted in a good accuracy (R (2) = 0.75, root mean squares error of prediction (RMSEP) = 0.17%, and ratio of prediction deviation (RPD) = 1.81).The validation of the calibration model using laboratory spectra provided comparatively better prediction accuracy (R (2) = 0.70, RMSEP = 0.15%, and RPD = 1.78), as compared to the online measured spectra (R (2) = 0.60, RMSEP = 0.20%, and RPD = 1.41).Although visual similarity was clear, low similarity indicated by a low Kappa value of 0.259 was observed between the online vis-NIR predicted full-point (based on all points measured in the field, e.g., 6486 points) map of SOC and NDVI map.

View Article: PubMed Central - PubMed

Affiliation: Vocational School of Technical Science, Uludag University, 16059 Bursa, Turkey.

ABSTRACT
This study explores the potential of visible and near infrared (vis-NIR) spectroscopy for online measurement of soil organic carbon (SOC). It also attempts to explore correlations and similarities between the spatial distribution of SOC and normalized differential vegetation index (NDVI) of a wheat crop. The online measurement was carried out in a clay vertisol field covering 10 ha of area in Karacabey, Bursa, Turkey. Kappa statistics were carried out between different SOC and NDVI data to investigate potential similarities. Calibration model of SOC in full cross-validation resulted in a good accuracy (R (2) = 0.75, root mean squares error of prediction (RMSEP) = 0.17%, and ratio of prediction deviation (RPD) = 1.81). The validation of the calibration model using laboratory spectra provided comparatively better prediction accuracy (R (2) = 0.70, RMSEP = 0.15%, and RPD = 1.78), as compared to the online measured spectra (R (2) = 0.60, RMSEP = 0.20%, and RPD = 1.41). Although visual similarity was clear, low similarity indicated by a low Kappa value of 0.259 was observed between the online vis-NIR predicted full-point (based on all points measured in the field, e.g., 6486 points) map of SOC and NDVI map.

Show MeSH
Related in: MedlinePlus