The Particle Size Causes a Change in the Determination of Soil Color Via the Nix Pro 2 Sensor

Usually, Soil Color is visually estimated in the field with the Munsell Soil Color Charts. Visual definitions are subject to uncontrolled effects that can alter results. Tools of spectral measurement allow for accurate, quick, and simple color readings. Our work aimed to evaluate the influence of granulometry on the determination of soil color using the Nix Pro 2 sensor. Eighteen soil samples of different particle sizes (granulometry) (2 mm, 0.297 mm, 0.149 mm, and 0.074 mm) were used and analyzed with the Nix Pro 2. The RGB (red, green and blue) values obtained in the analyzes with Nix ™ Pro 2 were converted to the Munsell standard through an R software script. Statistical analyzes of these three experiments were performed using the Scott-knott test at 0.05 significance and principal component analysis for the variables R, G, B, hue, value and chroma. The particle size affects the spectral behavior of soil samples for frequencies in the visible region, and the Nix Pro 2 color sensor can optimize soil color determination.