EUCALYPTUS PRODUCTIVITY, SOIL PHYSICAL PROPERTIES AND ORGANIC MATTER FRACTIONS INFLUENCED BY TRAFFIC INTENSITY AND HARVEST RESIDUES

The number of machine passes, types of wheels, and high soil moisture during harvest operations affect the soil compaction process. The impacts of these factors and alternatives to reduce them must be better understood. This study evaluated the impact of different traffic intensities of a loaded forwarder and the effect of different management conditions of eucalyptus harvest residues on productivity, soil physical properties, and organic matter at the end of the subsequent rotation in two Oxisols in the State of Minas Gerais, Brazil. The treatments consisted of a 2 x 3 factorial arrangement: two or eight machine passes between rows over crop residue without bark, crop residue with bark, or an area without residue. Eucalypt wood productivity losses due to soil compaction caused by forwarder traffic is mitigated by the presence of harvest residues, especially when bark is maintained in the area. Residue removal, and especially bark removal, leads to reduction in total organic C content and the more labile C and N fractions of the soil. Forwarder traffic in the harvest of the previous rotation of eucalyptus on soil without residues leads to losses in soil physical quality, with increased bulk density and resistance to penetration, and reduction in porosity and hydraulic conductivity. These negative effects were observed up to the end of the following rotation.