The determination of some physical characteristics of different particle sizes in soils with reflection spectroscopy

Abstract

The main objective of this study is to evaluate the ability of visible near-infrared reflectance spectroscopy (VNIRS) to predict diverse soil properties in grinding different particular size effect. In this study, 60 soil samples were collected from the fields include different soil ordo (Entisols, Inceptisols, Vertisols and Mollisols) in Isparta (Atabey) district Crushed samples were subjected into five different mesh sizes (4.76-2.00, 2.00-1.00, 1.00-0.50, 0.5-0.25 and <0.25 mm, respectively). Each soil samples were scanned with a visible near-infrared spectrometer, with a spectral range of 350 to 2500 nm, at five different particular sizes. The spectral reflectances were used to predict some physical properties of the soil (texture, field capacity and wilting point) using partial least squares (PLS) regression. PLS analysis was used to develop calibration models between smoothed-first derivative 6-nm-spaced spectral reflectance data and soil physical analysis measured clay, silt, sand, field capacity and wilting point. The results showed that while soils need to be crushed to pass through 0.25 mm sieve in order to determine wilting point and amount of clay, mesh size was found non-significant in determining sand, silt and field capacaity and the results obtained from the reflectance values taken from field samplings proved to be satisfactory. Key words: Texture, field capacity, wilting point, visible near-infrared reflectance spectroscopy (VNIRS).