Resistência físico-mecânica de um argissolo vermelho-amarelo sob colheita florestal de Eucalyptus dunnii

Abstract

With the significant increase in the productivity of forest sites, it is essential to implement techniques that aim to balance high crop yields and soil resilience, to minimize the impacts caused by compaction resulting from forest harvesting. This study aimed to evaluate the effects of the traffic intensity of wood harvesting machines (harvester and forwarder) on a loamy sandy clay Ultisol, with and without presence of the residual biomass from the eucalyptus harvest. The study was carried out in a commercial stands of Eucalyptus dunnii, with the following treatments of different traffic intensities, being: C (control without any traffic), H (one Harvester wheeling), H2F, H4F, H8F and H16F that consisted of a Harvester wheeling plus the sequence, respectively, of two, four, eight and sixteen wheelings of forwarder, where the last three treatments make up the wood extraction stage, with presence or absence of residual biomass. The experimental design was a randomized block with three replications. Soil samples, with preserved structure, were collect in volumetric rings in the layers of 0.00-0.10, 0.10-0.20, 0.20-0.40, and 0.40-0.60 m. The following aspects were evaluated: (i) the effect of the machines on the soil/residue: tire contact area, pressure applied by the machines on the soil, and layer of residual biomass; (ii) the composition soil properties bulk density, total porosity, macroporosity, microporosity, pore size distribution, water storage; and (iii) the functionality soil properties: air permeability, the saturated hydraulic conductivity, preconsolidation tension, and penetration resistance in the field. When associating composition and functionality soil properties, it was possible to observe that compression caused by harvesting machines wheeling can be beneficial in more sandy soils, by modifying the porous system to increase pores responsible for water retention in deeper soil layers. The number of forwarder wheelings in the same line will depend on the considered soil depth; overall, two and four passes in the presence of harvest residues, and only two passes in the absence of such residues.