PHYSICAL-HYDRICAL ATTRIBUTES AND ORGANIC CARBON ON ULTISOL AFTER 23 YEARS UNDER DIFFERENT MANAGEMENTS

Due to continued machinery, soil mobilization has caused considerable changes in both soil bulk density (physical attributes) and organic C content, risking crop yield reduction and negative environmental effects. In this context, this work aimed at assessing changes in both physical attributes and in organic C content of a Argissolo Vermelho-Amarelo surface horizon, subjected to no-tillage (NT) and conventional tillage with disk plow (DP), heavy harrow (HG), and disc plow plus harrow (DP+HG) for 23 years. A natural forest fragment (NF) was used as reference area. A randomized-block design with 8 x 12 m plots and four replications was used. Soil samples were collected at 0-5, 5-10, 10-20, and 20-40 cm depths in order to assess soil density, total organic carbon content, porosity, saturated hydraulic conductivity, and aggregate stability. Results showed that continued cultivation increases soil physical degradation, as evidenced by both macro porosity and total porosity reduction, aggregate stability, saturated hydraulic conductivity, total organic carbon, and soil density increase. The NT was found to best contribute to soil physical properties improvement and total organic carbon recovery in 0-5 cm surface layer.