Soil Pore Characterization Using Free Software and a Portable Optical Microscope

Total porosity (TP), determined by image analysis, pore type and pore size distribution were evaluated on impregnated soil blocks from an undisturbed Brazilian sandy loam soil using a digital portable optical microscope. The free software Image J (version 1.40g) was used for image analysis. Procedures for soil image collection and analysis were presented. The image analysis allowed the evaluation of pore sizes with diameters ranging from 20 to > 1 000 m. The following types of pores were also obtained: rounded, elongated and intermediate. The results allowed the characterization of the soil as moderately porous (TP = 21.6%). Rounded, intermediate and elongated pores were responsible for 11.6%, 31.7% and 56.7% of TP. In relation to pore size 51.1% of TP was in the 100-500 mu m size class and a third of TP came from the pores larger than 500 mu m.