ATRIBUTOS FÍSICOS DE UM NITOSSOLO VERMELHO CULTIVADO COM TRIGO, EM SISTEMA PLANTIO DIRETO, SUBMETIDO À COMPACTAÇÃO E ESCARIFICAÇÃO1/PHYSICAL ATTRIBUTES OF AN OXISOL CROPPED WITH WHEAT IN NO-TILLAGE SYSTEM, SUBJECTED TO COMPACTION AND SCARIFICATION

This study aimed to evaluate the influence of different levels of soil compaction on wheat yield grown in an Oxisol. The experiment was conducted at the Experimental Station of the Federal Technological University of Parana, Campus Dois Vizinhos, PR, Brazil. The treatments consisted of no-tillage (PD), tillage with additional compression (PDA) and tillage with mechanical scarification (PDE). The authors evaluated the density, porosity and resistance to penetration at every 0.05 m to 0.25 m in depth, as well as the productivity of wheat, grain weight and hectoliter weight. It was found that in the topsoil are the lowest soil densities, greater macroporosity and total porosity at the three situations, where in the layers below 0.05 m the treatments PD and PDA exceeded the critical value of 1.30 kg dm^sup -3^ for clayey soils. Additional compaction to the no-tillage system adversely affected the physical properties of the soil in the topsoil above 0.05m, where increases in the soil density, penetration resistance and reduced macroporosity and total porosity were observed.