This study was carried out at EMBRAPA-CNPAF, Santo Antônio de Goiás (GO), Brazil, in a clayey Oxisol, under three soil tillage systems, from 1992 to 1998.Corn was grown in the summer and common bean in the winter, under center pivot sprinkler irrigation.The objective was to compare the values of pH, Ca, Mg, P, and K of the soil, sampled at different depths under no-tillage to those from soil under moldboard plough tillage (conventional) and harrow tillage.Forty replicates were collected at 0-10, 0-20, 5-20, and 10-20cm soil depth under no-tillage, 0-20cm soil depth under moldboard plough tillage, and 0-15cm soil depth under harrow tillage.The Tukey test was used to compare the means of the chemical characteristics.The values of pH, Ca, Mg, and K varied according to the tillage system.The P and K had the highest variability while pH had the lowest.Sampling at 0-20cm depth under moldboard plough tillage showed pH, Ca, Mg, and K values similar to sampling at 0-10cm depth under no-tillage.For P, the correspondent sample depth under no-tillage was 10-20cm.
soil analysis; soil tillage; cerrado soil