Soil compaction. Tractor traffic effects on direct sowing systems

The present article evaluates the incidence of different traffic intensities on soil physical properties under a directsowing system in the continuos crop rotation wheat-soybean. The traffic treatments applied were six, eight, ten ortwelve consecutive passages of a tractor in the same track and a control plot without transit. The parameters used toquantify compaction were cone index and dry bulk density, measured before and after each traffic treatment, and comparedwith the control. The tractor used was a two wheel drive, 52.25 kW power engine, 3,020 kg total mass, 940 and2,080 kg on the front and rear axles, 7.50-16 and 16.9-34 tyre size respectively. Results showed that as the number ofpassages increased, the values of bulk dry density and cone index registered in the soil profile studied were higher.Moreover, a higher number of passages of light tractors (29.6 kN) induced subsoil compaction. The direct sowingsystem does not limit subsoil induced compaction in high intensity traffic situations.