The effects of machinery traffic on soil attributes following the adoption of no-till systems in tropical environments are still poorly documented. Numerous questions persist about the dynamic variation of soil structure and its interaction with machinery and equipments. The present study had the objective to evaluate the effect of time of adoption of no-tillage system and compare them to a conventionally tilled soil and a soil under a native forest using soil compressibility models. The evaluated systems were: PD1 (one year of adoption of no-tillage), PD4 (no-tillage for four years), PD5 (no-tillage for five years), PD12 (no-tillage for 12 years), one system under conventional tillage (PC for 18 years ) and another without use or intervention (native forest-MN) on a Dystroferric Red Nitosol. The time since adoption of the no-tillage system altered the soil compression performance at both depths (0-5 and 10-15 cm) through changes in the compression index and pre-consolidation pressure. The smallest capacity of load support was observed at the 0-5 cm depth and the highest at the 10-15 cm depth. Soils of all systems proved more susceptible to soil compaction at the 0-5 cm depth than at the 10-15 cm depth. The load support capacity of soils under no-tillage and conventional tillage systems presented the following sequence: PD5 < PD12 < PD1 < PD4 <FONT FACE=Symbol>@</FONT> PC for the 0-5 cm depth and MN <FONT FACE=Symbol>@</FONT> PD12 < PC <FONT FACE=Symbol>@</FONT> PD4 < PD5 for the 10-15 cm depth. The PD1 system presented a distinct behavior.
adoption time; preconsolidation pressure; capacity of load support; soil management
