Soil physical properties and organic carbon stratification rate in an oxisol after ten years under two different soil management systems

In the clay and heavy clay soils, compaction of the surface layer represents one of the limitations under no-tillage. Under such conditions, periodic soil tillage has been adopted. Other techniques, such as crop rotation are indicated for the physical management of the soil due to a larger input of organic matter and bioporosity of the soil. The objective of this study was to quantify some soil physical properties in an eutroferric Red Latosol (rhodic Eutrudox), the organic carbon content and the soil organic stratification rate after ten years of two soil management systems. The soil management systems included: crop rotation under no-tillage (NT), and crop-sucession under no-tillage, but with soil chiseling before the summer crop CNT). Larger values of bulk density were verified in NT and macroporosity and total porosity in CNT. In both management systems, the air-filled porosity was above 10 %, suggesting that the aeration conditions were appropriate for the plant roots. The soil water retention curve indicated that the soil under CNT retains more water than under NT at high potentials, but they are similar at potentials below -0.008 Wa. The soil penetration resistance (RP) was larger in NT down to the depth of 0.20 m, independently of the soil moisture content. Results suggested that with identical soil dryness the RP can reach restrictive values for plant growth in NT. Thus, management practices to maintain the soil moisture are necessary to keep the RP lower than the levels considered restrictive for plants. The soil organic content (SOC) was higher in NT down to a depth of 0.10 m, while higher values were observed at depths of 0.10-0.40 m CNT. The SOCstratification rate in the soil was 1.73 in NT while in CNT it was 1.24. Results show that this highest SOC concentration in NT may result in more stable soil physical conditions for crops.