The microbial biomass is a living component of the organic matter responsive to changes caused by different soil management systems. The objective of this long-term study was to determine microbial biomass carbon and nitrogen in response to different management systems in a clayey Red Latosol cultivated with corn in the Cerrado. The field experiment was conducted on an experimental area of Embrapa Cerrados, Planaltina, in the Federal District. Eight soil management systems with different implements and periods of crop residue incorporation were compared. Soil samples were collected from five layers: 0-5, 5-10, 10-20, 20-30, and 30-40 cm, with three replicates and in three sampling periods: before corn planting, 30 days after germination and at corn flowering. Treatments under no-till differed from each other regarding the microbial biomass Cmic and Nmic contents: while in one no-till treatment the soil cultivated by moldboard plow in the first year (PDAV) had a higher Cmic content, in the other no-till treatment the soil cultivated by disk plow in the first year (PDAD) had a higher Nmic content. This indicates that the effects in the soil profile caused by disk and moldboard plowing are still measurable, even after 22 years under no-till. In general, the greatest differences between no-till (PDAD and PDAV) or minimum tillage (chisel plow), and those with greater soil disturbance (disk and moldboard plow) were observed before planting, that is, before soil plowing and fertilization for the crop.
no-till; disk plow; moldboard plow; chisel
