Soil compaction is a problem in the Savanna region, where conventional soil tillage systems have caused excessive disaggregation of the arable layer, superficial crusts, and compacted subsuperficial layers. As an alternative, the farmers have adopted the no-tillage system. However, in various situations, an increase of soil bulk density and a decrease of macroporosity has been observed. This process is diagnosed as soil compaction and requires from the farmers the turnover of the soil. This work has the objective to verify how soil compaction affects physical and water transmission properties of soil. Artificially compacted soil columns were used to provide soil bulk densities of 1.0; 1.2; 1.4; and 1.6 kg dm-3. Water transmission properties were determined with tension infiltrometers at pressure heads of -0.5; -2.0; and -6.0 cm of water column. Increasing soil bulk density increased soil resistance to penetration and reduced linearly soil porosity and macroporosity. The flow-weighted mean pore size was reduced too decreasing soil hydraulic conductivity. This reduction was more pronounced at higher pressure heads. The reduction in pore size was partially compensated with the increase in the number of pores, at a pressure head of -2.0 cm of water. The method of tension infiltrometer was adequate to distinguish differences in water transmission properties of a soil submitted to different levels of compaction.
Phaseolus vulgaris; tension infiltrometer; hydraulic conductivity; soil porosity; bulk density
