Alterações em propriedades físico-hídricas e interpretação por imagens tomográficas da porosidade de um latossolo cultivado com plantas de cobertura

Abstract

A good condition of soil physical and structural quality is determined by porosity, which directly influences aeration, water and solute transfer, resistance to penetration and root branching. Although these interactions are studied through traditional techniques, the use of more modern techniques can bring more understanding of the effects of roots on soil structure. Computed tomography assists in this characterization by visualizing properties such as connectivity and pore volume. The inclusion of cover crops in soil management can promote biopores, conditioning their physical-water behavior and influencing the productivity and sustainability of agricultural systems. In two studies, it was evaluated that changes in the physical-water attributes of a typical Dystroferric Red Oxisol in direct planting would be detected after cultivation for three years of the summer cover plant species of crotalaria spectabilis, jack beans and pigeon pea in succession with wheat in the Northwest region of the state of Rio Grande do Sul, with the aim of identifying plant species with greater capacity to promote biological decompression. In the first, traditional techniques were used to evaluate soil density (Ds), total porosity (Pt), macroporosity (Ma), microporosity (Mi), soil air permeability (Kar) and stable infiltration rate (TIE). In the second study, computed tomography was used to evaluate pore volume, anisotropy, connectivity (Euler number) and pore tortuosity. To process the 3D images, they were converted into a 2D sequence, to which image treatments were applied to increase sharpness and obtain uniform contrast in the set of images. The segmentation was carried out in order to separate the mineral material from the organic material and pores, carried out by applying the global methods available in the ImageJ/Fiji software. The variables were statistically analyzed using the “R” program, Anova and 5% Tukey test. The roots of cover crops proved to be efficient in promoting stable biopores, contributing to improving indicators. These channels initiated by the decomposition process provide a favorable environment for subsequent culture. The computed tomography technique is a tool that enhances the interpretation of physical parameters in relation to traditional measurement methods, allowing better assertiveness.