The potential of NIR spectroscopy to predict soil texture and mineralogy in Cerrado Latosols

Near-infrared reflectance spectroscopy (NIRS) has been accepted as a fast method to evaluate various soil constituents. However, very few studies have used NIRS as a predictor of the textural and mineralogical content of tropical soils. The objective of this study was to investigate the potential use of NIRS as a tool for assessment of diverse soil properties, with specific attention to the prediction of properties related to the mineralogy of a wide range of Latosols from the Cerrado region of central Brazil. The reflectance of the soil samples, 148 in total, taken from 0.0 to 0.2 and 0.6 to 0.8-m depth, was determined in the near-infrared region between 1100 and 2500 nm at 2-nm intervals with a NIRS spectrophotometer. Our results show that for soil sampling corresponding to a large-scale map and taking into account the variability of Latosols over a wide region, NIRS can predict most of the mineralogical properties of the Latosols accurately. Near-infrared spectroscopy did not predict most of the physico-chemical characteristics of soils accurately, in particular those that are largely dependent on agricultural practice, such as pH or CEC. However, the main characteristics that correspond to soil constituents (organic matter and clay content) were relatively well predicted.