Impact of Self-Propelled Sprayer Traffic on Ferralsol Physical Properties in Southern Brazil

To study the effect of repeated machinery traffic on soil physical properties. The aim was to evaluate the impacts of multiple passes of a self-propelled sprayer on a Ferralsol. A trial was performed on a clayey-textured humic Ferralsol under conventional tillage. Sprayer traffic was applied in a strip-plot with four treatments: no traffic (T0), one pass (T1), three passes (T3), and seven passes (T7) of the self-propelled sprayer. Physical properties such as total porosity (TP), macroporosity (Mac), microporosity (Mic), soil bulk density (rho(b)), soil resistance to penetration (PR), and aggregate stability (ASI) were determined down to 0.40 m of depth, under the track wheels. Traffic-induced changes in soil physical properties were observed to 0.20 m depth, but the main impacts occurred at 0.10 m and comprised increased rho(b) and PR, and decreased Mac and ASI. Even though Mac reduction reached critical values (Mac < 0.10 m(3)m(-3)) under the wheel tracks after seven passes, PR was below 2.0 MPa at all depths. Despite affecting soil physical properties, self-propelled sprayer traffic did not cause severe physical degradation of the Ferralsol or changes in the soil structure to an extent that would severely limit root growth.