Tempo de implantação do sistema plantio direto e propriedades físico-mecânicas de um latossolo

Abstract

Which the effect of no-tillage system on the soil physical and mechanical properties along the time? With this question, the objective this study was to evaluate the effect of the no-tillage system along the time on the physical and mechanical properties of the soil, as well as, the behavior of the compressive properties along the use of Oxisol Red. The experimental design used was of randomized block with bi-factorial 5 x 2, with five different times of implantation management and two levels of traffic. The implantation times of the no-tillage used were: SD0 - 0 years (2 months); SD2 - 2 years; SD4 - 4 years; SD5.5 5.5 years and SD14 - 14 years. The level of traffic was without and with traffic. Soil samples were collected in three layers: 0.0 0.06 m, 0.07 0.14 m and 0,15 0.22 m. The SD0 demonstrated increase macroporosity that resulted in high saturated hydraulic conductivity thus increased the air permeability, in all the soil layers studied. With the increase of the time implantation of the no-tillage system, increased of microporosity and organic carbon, in the layer 0.00 0.06 m. The SD5.5 and SD14 was the treatments that retain more water independently of the traffic from machines. In the beginning of the no-tillage system had a smaller bulk density and occurrence of larger relative deformations, while after some years, there are an elevation of the bulk density and the reduction of deformation that extends until the fifth and a half year, where, there is a reduction of the bulk density and deformation to the 14th year. The traffic doesn't generate enough differences in the compression index, pré-consolidation tension, bulk density and the degree of water saturation that soil to 33 kPa. In the 0.07 0.14 m of soil, occurred an elevation of the bulk density and reduction of the avoid ratio independently of the time implantation of no-tillage. The degree of water saturation influenced the deformation until the 5th and a half year of use of no-tillage, after that, action of the structure reduced your effect in the soil.