02388naa a2200241 a 450000100080000000500110000800800410001910000170006024501100007726000090018752015470019665300370174365300310178065300260181165300190183765300210185670000170187770000240189470000170191870000170193570000160195277301780196811247812016-02-11       2015    bl uuuu     u00u1 u    #d1 aSILVA, E. B.  aModeling soil texture using a limited region of the visible/near infrared spectra.h[electronic resource]  c2015  aSoil particle size is an attribute of fundamental importance when defining soil use and management. Proximal Soil Sensing (PSS) attempts to facilitate the acquisition of a larger amount of soil spatial data using a faster and less laborious technique, although an impediment to a wider application of PPS is the equipment cost. Thus, the objective of this study was to evaluate the capacity of a limited spectral acquisition region (325-1075 nm) for modeling soil texture. Soil samples were collected in the southwest part of Marombas river watershed located near the center of Santa Catarina state, south of Brazil. A total of 42 soil profiles were sampled according to the Globalsoilmap.net protocol. A data set of 166 samples was used for modeling and a different data set, 71 samples, was used for model validation. Diffuse reflectance spectroscopy of sieved samples (2 mm) was collected with a spectrometer FieldSpec HandHeld II (ASD Inc.). Savitzky-Golay second derivatives were calculated and used in partial least-squares regression modeling with Unscrambler X 10.3. Calibration and validation data set showed homogeneity of variance, as well as, passed the test of comparison between the mean. Sand, clay and silt RMSEP (%) was of 6.56, 7.16 and 5.88, respectively. The R² for validation was 0.15, 0.49 and 0.42 for the same attributes. RPD was below 1.4 for all three attributes. Those results show that modeling soil texture with a limited spectral region might require some previous stratification, by samples depth, for example.  adiffuse reflectance spectroscopy  adigital soil morphometrics  aproximal soil sensing  asoil attribute  asoil reflectance1 aCATEN, A. T.1 aDALMMOLIN, R. S. D.1 aDOTTO, A. C.1 aSILVA, W. C.1 aGIASSON, E.  tIn: INAUGURAL GLOBAL WORKSHOP ON DIGITAL SOIL MORPHOMETRICS, 1., 2015, Madison, Wisconsin USA. Abstracts... Madison, Winsconsin: University of Wisconsin-Madison, 2015. p. 15