Agricultural machine traffic causes soil compaction in vineyards, which may be accentuated between the rows due to greater intensity of traffic. The aim of this study was to evaluate the variability of soil physical properties as a function of the sampling position in relation to the plant row in commercial vineyards of the Bordô variety planted directly in the soil and subjected to different management practices. In February 2012, three vineyards were selected in the municipality of Major Gercino, southern Brazil - one without the use of agricultural machinery (vineyard 1 with six years of age) and two that use machines between the rows (vineyards 2 and 3, with eight and 17 years of age, respectively). Undisturbed soil samples were collected in the crop row (Cr), the wheel row (Wr), and between the crop row and the wheel row (Br) at the 0.00-0.05, 0.05-0.10, 0.10-0.15, and 0.15-0.20 m depths. We evaluated bulk density (Bd), resistance to penetration (Rp), pore classes (macropores - MaP, mesopores - MeP, micropores - MiP, and total porosity - TP), aggregation and aggregate stability indices (mean geometric diameter of air-dried aggregates - MGDad, and water stable aggregates - MGDws, and aggregate stability index - ASI), gravimetric moisture (Gm), and particle density and particle size distribution in the soil. Compaction increased in the direction from the Cr to the Wr. The occurrence of traffic, in general, negatively affected the properties evaluated. Among the sampling positions, the greatest values of Bd and Rp occurred in the Wr, where the Rp reached critical values for root development. In the mechanized vineyards, high values of Rp and low values of MaP were found in the 0.00-0.05 and 0.05-0.10 m layers. Aggregates of greater diameter and the lowest ASI were also found, which indicates deterioration of soil physical quality. In vineyard 1, there was less variability of the physical properties; while in vineyard 2 the negative effect of machine traffic was observed, especially for the properties related to aggregation and high MiP. In vineyard 3, greater indices of Rp and Bd were observed, as well as the lowest value of MaP. Therefore, in relation to the vineyards studied, an increase in soil physical degradation was caused by machine traffic (vineyards 2 and 3). Among the soil collection positions and the vineyards, separation of the Wr position of vineyard 3 was seen by means of principal component analysis, stemming from the Bd and Rp properties, from which it may be inferred that the management adopted in the Wr position of vineyard 3 is leading to greater degradation of soil physical quality.
variability of soil physical properties; Vitis labrusca; principal component analysis
