title: Online measurement of soil organic carbon as correlated with wheat normalised difference vegetation index in a vertisol field.
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.
authors.affiliation: Vocational School of Technical Science, Uludag University, 16059 Bursa, Turkey.
authors.forename: Yücel
authors.initials: Y
authors.lastname: Tekin
authors.affiliation: Vocational School of Technical Science, Uludag University, 16059 Bursa, Turkey.
authors.forename: Yahya
authors.initials: Y
authors.lastname: Ulusoy
authors.affiliation: Agricultural Faculty, Uludag University, 16059 Bursa, Turkey.
authors.forename: Zeynal
authors.initials: Z
authors.lastname: Tümsavaş
authors.affiliation: Environmental Science and Technology Department, Cranfield University, Bedfordshire MK43 0AL, UK.
authors.forename: Abdul M
authors.initials: AM
authors.lastname: Mouazen
mesh_terms: D018533:Biomass; D002138:Calibration; D002244:Carbon / Q000032:analysis*; D009862:Online Systems; D012987:Soil / Q000737:chemistry*; D019265:Spectroscopy, Near-Infrared / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D014908:Triticum / Q000254:growth & development*
chemical_list: D012987:Soil; D002244:Carbon
references.citation: Sensors (Basel). 2013 Aug 08;13(8):10177-90
references.pmid: 23966186
references.citation: Biometrics. 1977 Mar;33(1):159-74
references.pmid: 843571