Qualidade física do solo em desbaste mecanizado de Eucalyptus saligna

Abstract

Machine traffic is the main cause of compaction of forest soils, due to the fact that deformations occur in the soil, caused by the pressure of the mass of the machines, either at the time of the cutting or even the wood bucket. In this sense, this work had the objective of evaluating the soil compaction caused by the traffic of machines in the mechanized thinning operation in Eucalyptus saligna Smith. The study was carried out in a forest, in the city of Butiá, Rio Grande do Sul. Changes in soil physical properties were evaluated in three treatments: no traffic, after cutting and after full wood loading. Two study sites were demarcated, in which the forest inventory, the biomass survey and the volumetric ring collections were determined in the soil to determine microporosity, macroporosity and density. The experimental design was the fully randomized (DIC), of two - factorial arrangement, with subdivided plots. For the comparison of the physical attributes, the Tukey test at 0.05 of significance was used. The results evidenced that the mechanized thinning operation caused soil compaction. There was an increase in the values of soil density, mainly in the condition after the bucket, which resulted in average values of 1,638 Mg.m-³, 1,674 Mg.m-³, 1,617 Mg.m-³, for the layers of 0 to 5 cm, 5 to 10 cm and 10 to 20 cm, respectively. These values exceeded the density considered critical for clayey soils, ranging from 1.40 to 1.60 Mg.m³. There was also a decrease of macropores, with values close to and below the considerable limit as detrimental to the development of plants (0.10 m³ m-³). The knowledge of soil deformations caused by forest operations contributes to the improvement of future processes, with the aim of assessing the physical quality of the soil, in order to offer beneficial conditions to the growth of the plants.