The structural soil modifications caused by different tillage systems can result in more or less intense compaction, which interferes with soil penetration resistance, bulk density and porosity, influencing root growth and crop yields. The objective of this work was to evaluate the effect of compaction on particular characteristics of a Red Latosol and associate them with root growth and maize yield. The main treatments consisted of six compaction levels, induced by controlled tractor traffic and the secondary treatments of two layers with four replications. Undisturbed soil samples were collected in the layers 0-0.10 and 0.10-0.20 m for determination of soil penetration resistance, bulk density and soil porosity. To determine the root density, surface, diameter and dry matter soil samples were collected in the layers 0-0.10; 0.10-0.20 m, in each plot. Tractor traffic on the soil caused higher compaction levels in the surface layer which resulted in higher bulk density and greater root surface. Root dry matter and diameter increased linearly with the increase of the soil penetration resistance. It was verified that values of to soil penetration resistance between 1.03 and 5.69 MPa affected the root system morphology, reducing the crop yield by 2.581 Mg ha-1, while not impeding root growth.
penetration resistance; water content; Oxisol; Zea mays
