Quantifying soil pores geometric properties using fluorescent dye method

Soil porosity plays the major role in relation with soil genesis, soil processes control and its interactions with the environmental factors and translocation of water and solutes. The heterogeneity of soil porosity components is simplified by considering some assumptions such as taking into accounr all of the pores do actively and are spherical. Micromorphological approaches by direct observation and determination of soil pores geometry prepares detailed characterization of soil pores. The aim of this study was quantifying soil pores geometric properties using flouerecent dye method. 39 undisturbed soil samples impregnated with a mixture of resin-acetone containing flouerecent dye, dryed out and cut. Then 40 digital images were taken from each sample under ultraviolet light. The images were thresholded until the soil pores distinguished as white from the matrix. The results of pores based on area, perimeter, elongation, compaction, roundness, ferret diameter, long and short axis diameters were classified visually. The quantitative results of pores area showed that the pores smaller than 100 μm2 in the plough layer (depth 29% in the plough pan due to compaction. Pores with > 100 μm2 area in plough layer increases > 80% of total porosity. The dominant compaction class was the (0.3-0.5 unit less) that its maximum percent was (56.94%) in the depth of 35-30 cm. According to the elongation index the most elongated pores (the class