The operation of forest traffic is related to use of machines that pass through the same line repeatedly or randomly, which may cause soil compaction, changing the environment of root growth system development and reducing the productivity. Besides the number of passes, the wood load carried may also affect soil compaction, when the applied pressures by machines exceed soil load support capacity. The objectives of this study were: a) to propose a load support capacity model for a Oxisol (Red-Yellow Latosol, LVA) as a function of preconsolidation pressure and moisture content; b) to determine, through the model, the effect of traveling and load intensity of a forwarder on the soil structure. To obtain the load support capacity models, 20 undisturbed soil samples were collected in the depth of 0-3 and 10-13 cm, at a site where there was no traffic. Also 10 undisturbed soil samples were collected for each depth where the Forwarder passed though 2, 4 and 8 times, and where the Forwarder passed in the same line 4 times with 1/3 (3 m³), 2/3 (6 m³) e 3/3 (9 m³) of its load. The undisturbed soil samples were used in the uniaxial compression tests. The particle size distribution, organic matter content, particle density and soil density were also determined. The load support capacity model for the Oxisol is expressed by the equation s p = 10 (2,71 - 1,36 U). All the traffic intensities caused soil compaction in the two depths, where four passes caused highest soil compaction, and as the Forwarder load increased, the soil compaction also increased in the two depths.
Soil compaction; Preconsolidation pressure; Forest mechanization
