The integration between agriculture and cattle-raising in some areas can restrict the use of no-tillage system in clayey soils, due to soil surface compaction, which restricts root growth and limits crop yield. The objective of this study was to evaluate the changes in soil physical properties and maize parameters caused by animal trampling preceding the summer crop, under two tillage systems. The degree of degradation of the cultivated soil compared to the native forest was also evaluated. The experiment was carried out in Lages, Southern Brazil, in an Ultisol, using conventional tillage and no-tillage with corn in the summer and oat in the winter for grazing. Macropores, micropores, total porosity, bulk density, saturated soil hydraulic conductivity, resistance to penetration and corn parameters were determined. The pressure applied by animal trampling and soil management systems degraded the soil structure in comparison to the native forest. This was observed by the reduction of the macropores, total porosity and saturated soil hydraulic conductivity and through an increase of the bulk density. Under the no-tillage system, there was an increase of the resistance to penetration, mainly in the layer of 0 to 0,15 m. These alterations in soil structure reduced maize plant height, number of green leaves, weight and number of grains per ear under no-tillage compared to conventional tillage. Such observations show the evidence that growers should avoid the use of heavy machines and animal trampling under no-tillage, particularly in clayey soils and when soil moisture is above the friability point.
soil compaction; animal trampling; no-till; conventional tillage