Resumo

GELATI, Pablo Raul; SARLI, Guillermo Oliverio; LOZANO, Luis Alberto  e  FILGUEIRA, Roberto Raul. Fractal study of the distribution of particles and pseudoparticles in soils of the pampean meadow. Cienc. suelo [online]. 2019, vol.37, n.1, pp.147-157. ISSN 1850-2067.

Fractal geometry allows describing theoretically structures of diverse nature. From this it obtain the fractal dimension of fragmentation (D), which is related to the partitioning and scaling presented by them, and which has been used in the characterization and study of the size distribution soil particle (DTP). It was proposed to apply the fractal model and investigate the process of micro-structuring in six agricultural soils of the Pampean meadow that have contrasting DTP. The DTP and D were obtained under two pretreatments, one without organic matter (SMO), maximum dispersion, and the other with organic matter (CMO), thus preserving the microstructure. The fractal model applied to the DTP with the SMO pretreatment, in silty loam soils, was able to describe on average 98% of the mass analyzed; in sandy loam soil it adjusted to 50 μm, describing 38% of the mass, while the sandy loam soil did not adjust to the fractal model. With the larger sizes of the sands, they obtained D close to 3, showing Euclidean characteristics, not fractals. The DTP for the CMO pretreatment had similar behavior among the evaluated soils, compared to the SMO pretreatment, the percentages of the fractions corresponding to the clay and silt sizes decreased; and the percentage of the size of the sands increased. These fractions, CMO, were called "apparent clay, silt and sand". The D from the SMO pretreatment were greater than those obtained under the CMO pretreatment. The decrease of the D of the pretreatment CMO, was interpreted as an apparent thickening of the soil product of the microstructure by organic matter (OM). The fit between the contents of apparent clays vs OM was not significant (p = 0.37). The apparent silt fraction vs OM, adjusted significantly to a negative exponential function while the contents of the apparent sands vs OM adjusted significantly with a positive exponential function. The variations of OM significantly modify the microstructure in the silt and sand sizes while the fraction of clay size would be independent of the OM content of the soil, in the analyzed range. In temperate Pampas soils, with a proportion of clay + silt close to 90%, the OM by microstructure reduces the contents of clay and silt size particles, increasing the sand size to values close to 55% and these modifications can be interpreted using the model fractal.

Palavras-chave : Sedimentation; soil texture; fragmentation.