caa a22 4500 445864524 CHVBK 20180317145453.0 cr unu---uuuuu 170323e20110601xx s 000 0 eng 10.1007/s11119-010-9173-6 doi (NATIONALLICENCE)springer-10.1007/s11119-010-9173-6 Combined use of hyperspectral VNIR reflectance spectroscopy and kriging to predict soil variables spatially [Elektronische Daten] [A. Bilgili, Fevzi Akbas, Harold van Es] Hyperspectral visible near infrared reflectance spectroscopy (VNIRRS) and geostatistical methods are considered for precision soil mapping. This study evaluated whether VNIR or geostatistics, or their combined use, could provide efficient approaches for assessing the soil spatially and associated reductions in sample size using soil samples from a 32ha area (800×400m) in northern Turkey. Soil variables considered were CaCO3, organic matter, clay, sand and silt contents, pH, electrical conductivity, cation exchange capacity (CEC) and exchangeable cations (Ca, Mg, Na and K). Cross-validation was used to compare the two approaches using all grid data (n=512), systematic selections of 13, 25 and 50% of the data and random selections of 13 and 25% for calibration; the remaining data were used for validation. Partial least squares regression (PLSR) analysis was used for calibrating soil properties from first derivative VNIR reflectance spectra (VNIRRS), whereas ordinary-, co- and regression-kriging were used for spatial prediction. The VNIRRS-PLSR method provided better prediction results than ordinary kriging for soil organic matter, clay and sand contents, (R 2 values of 0.56-0.73, 0.79-0.85, 0.65-0.79, respectively) and smaller root mean squared errors of prediction (values of 2.7-4.1, 37.4-43, 46.9-61, respectively). The EC, pH, Na, K and silt content were predicted poorly by both approaches because either the variables showed little variation or the data were not spatially correlated. Overall, the prediction accuracy of VNIRRS-PLSR was not affected by sample size as much as it was for ordinary kriging. Cokriging (COK) and regression kriging (RK) were applied to a combination of values predicted by VNIR reflectance spectroscopy and measured in the laboratory to improve the accuracy of prediction of the soil properties. The results showed that both COK and RK with VNIRRS estimates improved the predictions of soil variables compared to VNIRRS and OK. The combined use of VNIRRS and multivariate geostatistics results in better spatial prediction of soil properties and enables a reduction in sampling and laboratory analyses. Springer Science+Business Media, LLC, 2010 Soil variation nationallicence Visible near infrared reflectance spectroscopy (VNIRRS) nationallicence Partial least square regression (PLSR) nationallicence Kriging nationallicence Cokriging nationallicence Regression kriging nationallicence Bilgili A. Department of Soil Science, Agriculture Faculty, Harran University, 63300, Sanliurfa, Turkey aut Akbas Fevzi Department of Soil Science, Agriculture Faculty, Gaziosmanpasa University, 60100, Tokat, Turkey aut van Es Harold Department of Crop and Soil Science, Cornell University, 14853-1901, Ithaca, NY, USA aut Precision Agriculture Springer US; http://www.springer-ny.com 12/3(2011-06-01), 395-420 1385-2256 12:3<395 2011 12 11119 https://doi.org/10.1007/s11119-010-9173-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11119-010-9173-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Bilgili A. Department of Soil Science, Agriculture Faculty, Harran University, 63300, Sanliurfa, Turkey aut NATIONALLICENCE 700 1- Akbas Fevzi Department of Soil Science, Agriculture Faculty, Gaziosmanpasa University, 60100, Tokat, Turkey aut NATIONALLICENCE 700 1- van Es Harold Department of Crop and Soil Science, Cornell University, 14853-1901, Ithaca, NY, USA aut NATIONALLICENCE 773 0- Precision Agriculture Springer US; http://www.springer-ny.com 12/3(2011-06-01), 395-420 1385-2256 12:3<395 2011 12 11119 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer