The automatic recognition and measurement of soil pore types by image analysis and computer programs

Abstract

A system, ANOPOR, has been developed which uses the Quantimet 720 image analyser to recognize and measure the different types of pores in impregnated soil blocks. The system is concerned with three types of pores: channels, planar voids (cracks and fissures) and vughs but is not suitable for highly interconnected pore patterns. Each of the three types has a different origin and function and presents a different two-dimensional (2-D) shape when sectioned.A learning set consisting of these three pore classes was used to teach the system how to recognize statistically soil pores in images using measurements made by Quantimet. To describe the pore outlines in 2-D, shape factors giving the best class separation of the learning set in the pattern space were derived. Bayes equation was used to give the probability of a pore belonging to a particular class by comparing its position in the pattern space with the learning set. Class boundaries were determined which ANOPOR uses to allocate each pore in any image to the most likely class. The system measures the proportion of the pore space attributable to each class and the perimeter and intercept density for each. The system is used to measure the pore patterns in three soil horizons.

Tráfego de máquinas agrícolas e alterações de bioporos em área sob pomar de laranja

“…Nesse ponto, os poros de empacotamento desapareceram, dando origem a poros tipo cavidades e câmaras, os quais estão relacionados com os processos de compactação do solo (Ringrose-Voase & Bullock, 1984). Os poros oriundos da atividade biológica (bioporos) permaneceram; no entanto, tiveram o seu tamanho reduzido.…”

“…Outro exemplo de poros provenientes da alteração da estrutura, por meio da compactação, são as cavidades. Ringrose-Voase & Bullock (1984) sugerem que a formação das cavidades está relacionada com o adensamento ou com a compactação dos poros de empacotamento, mas, segundo Brewer (1976), as cavidades são formadas a partir da freqüente atividade da fauna no solo.…”

A novel method for measurement and characterization of soil macroporosity

“…Most of these methods employ the use of thin section analysis (12,14), soil profile photography (15,16), or dye tracers (13,17) to define the macropore area of interest. Then, the size, shape, and configuration of pores are quantified using an image analysis system (14) or manual measurements (12). Although the image analysis system is a preferred method for these types of determinations, the high cost associated with this equipment and degree of expertise needed to operate the unit may not justify its use as a general analytical tool.…”

Changes in pore structure in a no-till chronosequence of silt loam soils, southern Ontario

“…1B). The functional properties of a soil structure dominated by packing pores include rapid infiltration of water and easy root penetration and migration (RingroseVoase and Bullock 1984). Figure 1C marks an earthworm channel that has been intersected by the slicing of the thin section.…”