Long-term effects of no-tillage on dynamic soil physical properties in a Rhodic Ferrasol in Paranل, Brazil

No-tillage has been adopted worldwide as a strategy to reduce the negative effects of soil erosion in conventional tillage. However, no-tillage can lead to over-compaction of the soil, which can have detrimental effects on soil structure and on crop yield. The objective of this study was to evaluate the soil physical functionality of a Rhodic Ferrasol under long-term no-tillage. The following physical properties were measured: dry bulk density (Db), total porosity (Pt) and macroporosity as well as saturated hydraulic conductivity (Ksat) and intrinsic air permeability (Ka). Physical quality of the soil was also evaluated by the S index at each depth increment. The study was carried out in a Rhodic Ferrasol under a 14-year old, no-tillage system in Ponta Grossa, Paraná, Brazil. Undisturbed soil samples were collected at depths of 0–0.10, 0.20–0.30, 0.40–0.50, and 0.60–0.70 m. The soil properties such as dry bulk density, total porosity and macroporosity showed the presence of a denser layer at a depth of 0.20–0.30 m. The Db and Pt values in this layer were significantly different from the other layers. However, the values of 1.23 Mg m−3 for Db, 0.52 m3 m−3 for Pt, and 0.17 m3 m−3 for macroporosity were all still adequate for the growth and development of roots at this layer. The values of Ksat and Ka were higher at the surface layer than deeper layers. The lowest values were around 80 and 70% in comparison with surface, respectively to the depths of 0.40–0.50, and 0.60–0.70 m Ksat and Ka values were 7.79 × 10−5, 2.76 × 10−5, 1.58 × 10−5, and 1.91 × 10−5 m s−1, and Ka values were 3.70 × 10−11, 2.04 × 10−11, 7.69 × 10−12, and 1.10 × 10−11 m2 for the depths of 0–0.10, 0.20–0.30, 0.40–0.50, and 0.60–0.70 m, respectively. This demonstrated that better conditions for the exchange of gases and water existed in the layers above 0.30 m. The S index indicated that the soil had good structure in all layers studied, with values above 0.035, but that a small increase in Db in the 0.20–0.30 m layer could lead to deterioration of the soil structural quality. The long-term use of no-tillage resulted in increases of organic carbon and pore connectivity in the surface layer, providing functionality in the soil.