Atributos físicos e efeito do diâmetro dos agregados na resistência tênsil e friabilidade de solos com e sem caráter coeso

Abstract

The use of soil quality indicators is relevant for its management and conservation. In this perspective, physical indicators such as density, tensile strength of aggregates/clods and friability make it possible to monitor changes that occur in the soil, whether due to natural or anthropogenic causes. The hypotheses that: i) horizons with cohesive character differ from horizons without this character in terms of granulometry, soil density and tensile strength of aggregates/clods; and ii) the use of the diameter of the aggregates/clods obtained by the average of the opening of the meshes of the sieves to calculate the tensile strength results in different values ​​from those obtained with the real diameter in horizons with and without the cohesive character. As a general objective, we sought to know the granulometry, soil density, tensile strength considering the diameter of the aggregates/clods obtained by the average of the mesh opening of the sieves and actual aggregates/clods and to calculate the friability by the coefficient of variation of the tensile strength in soils with and without cohesive character. Tensile strength data collection was carried out in seven soils (Ultisols and Oxisol) considering two horizons (with and without the cohesive character). For each horizon, particle size analyzes were performed in ten repetitions; likewise, ten aggregates/clods were selected for measuring density and ten for tensile strength. Data were subjected to analysis of variance, Tukey test (both by Sisvar software), and multivariate analysis (by SAS software). The results showed that the particle size, density and tensile strength differ significantly between horizons of soils with and without the cohesive character; the tensile strength values ​​differ significantly when the methods for obtaining the diameter of the aggregates/clods are considered – being smaller when the diameter is measured directly – and result, although in few situations, in different friability classes for the same analyzed horizon.