INVESTIGATION AND ASSESSMENT OF SOIL DENSITY CHANGED BY REPEATED PASSES OF MIDDLE-WEIGHT TRACTORS WITH DIFFERENT DRIVE SYSTEMS

This work presents the investigation of the influence of repeated passes of medium-weight tractors with single wheels and additional wheels on the soil density to the depth of 0.4 m. The experiments were carried out in the Greater Poland Region (Poland), on light soil (Luvisol, loamy sand). The soil density was analysed in the arable layer at the two depths of 0.08–0.12 m and 0.18–0.22 m and in the plough pan at a depth of 0.30–0.34 m. The tractors weighing 52.1, 62.8 and 71.8 kN equipped with single wheels (standard wheels) and tractors weighing 52.1 and 71.8 kN equipped with additional wheels were used in the experiments. The research proved that repeated passes of the tractors with standard and addition wheels caused a linear or non-linear (logarithmic) increase in the soil density in the arable layer. Only light tractor 52.1 kN with dual wheels caused soil density increase in the hard pen. The above soil density changes inconsistent depend on the weight tractors and mean tractor pressure. Repeated passes of tractors with additional wheels resulted in lower soil density in the arable layer especially by second and third pass. A larger number of passes of middle-weight tractors with standard wheels as well with additional wheels increases the risk of reduced yield of cultivated plants.