ChileanJAR

Total organic carbon (CO), microbial biomass carbon (CBM) and mineralizable carbon (Cmin) were determined on three moments of corn cycle in a continuous maize field trial under three different tillage systems. CO distribtion depended of tillage system, depth and sampling time, existing a significative interaction between tillage system and soil depth. CO values were highest in direct drilling along aH the crop cycle for 0-5 cm depth. In conventional and reduced tillage CO values were scanty sensitives to sampling time. CBM showed a similar distribution pattern than CO, although percentage differences between tillage systems were greater than in total organic carbono Cmin was highest in the most conservatives tillage systems, and its distribution pattern was in agree with the CBM one. Residues distribution and soil condition under direct drilling, promote the best soil organic matter conservation, independently of crop cyc1e.