Farming and cattle-raising integrated system is an alternative to increase farmers' yield in southern Brazil (29º 45´south and 53º 42´ west Greenwich). However, grazing and, or, soil tillage may cause soil compaction at levels that can affect root growth and crop yield. The effect of animal trampling in continuous grazing during winter/spring (cold season) and soil management system effects on soil compaction, chemical attributes and root distribution were studied. The soil used was a Red-Yellow Podzolic (Hapludalf), with a loam surface texture. A cold season pasture composed of oats (Avena strigosa Schreb) and italian ryegrass (Lolium multiflorum L) was seeded, and an animal load adjusted to pasture growth was maintained. In December 1996, corn (Zea mays L) was planted for silage production, using the following treatments: no tillage after grazing, no tillage without previous grazing, conventional system after grazing, and conventional system without previous grazing. The evaluations shown in this study were related to the third-year data of the experiment, with a grazing period of 107 days. Forty-five days after corn emergence, trenches were dug (100 x 40 cm) for drawing the root distribution and collecting soil samples, in 5 cm increments, for soil chemical analyses, bulk density and root density determinations. Root distribution drawings showed more root bulk in the conventional system compared to no tillage, similarly to the results with Newman's counting method (root density). Animal trampling had no effect on soil physical properties, because pasture biomass was kept around 1.0 Mg ha-1 of dry matter. Soil bulk density, for the 5-10 cm depth, was 1.41 Mg m-3, for no tillage with and without previous grazing. For the conventional system, soil bulk density was of 1.15 Mg m-3, for previous grazing, and of 1.12 Mg m-3, for non-grazed area. Grain (4.55 Mg ha-1) and silage (34.66 Mg ha-1) yields were not affected by grazing or soil tillage. Soil tillage system had a greater influence on soil compaction than animal trampling, under controlled animal load adjusted to pasture growth.
no tillage; conventional tillage; animal trampling; root