The objective of this work was to evaluate the chemical attributes in a Xanthic Ferralsol under different tillage systems in the cerrado of Piaui State, Brazil. Four tillage systems were evaluated: three-year-old conventional tillage; no-tillage with three (NT3) and five years old (NT5), using millet as cover crop; and no-tillage with nine years old (NT9), of which seven years used millet as cover crop and two used forage. A native cerrado area was taken as reference. Soil samples were collected in wet and dry seasons at soil depths, 0.00-0.05, 0.05-0.10, 0.10-0.20 and 0.20-0.40 m, and analyzed for pH, Al 3+, H+Al, Ca 2+, Mg 2+, K +, sum of bases (SB), effective (t) and potential (T) cation exchangeable capacity, base (BS) and Al 3+ saturation (m%), available P and total organic carbon (TOC). The system NT9 showed the highest values of pH and lowest of Al 3+, H+Al, and m%. The highest values for Ca 2+, K, SB, t, T, V% and P, were observed under NT5 and NT9, until 0.20 m depth. The highest TOC contents were verified also under NT5 and NT9, except for 0.00-0.05 m soil depth. Organic matter accumulation associated with pasture under no-till increases TOC content at deeper soil layers in the dry period.
