Economically viable alternatives for winter soil use in southern Brazil are scarce. During this period, pasture cultivated under crop-livestock system is an alternative. The objective of this study was to evaluate the effect of different winter soil uses on weed infestation in maize cultivated in succession. Two experiments were carried out from May, 2006 to April, 2007. Five alternatives of winter soil use were investigated: (1) multi-cropping with black oat+ryegrass+vetch+arrow leaf clover without grazing and nitrogen fertilization (multi-cropping cover); (2) the same multi-cropping, with grazing and nitrogen fertilization, 100 kg ha -1 of N (pasture with N); (3) the same multi-cropping, with grazing and without nitrogen fertilization (pasture without N); (4) oil seed radish, without grazing and nitrogen fertilization (oil seed radish); and (5) natural vegetation, without grazing and nitrogen fertilization (fallow). Cover crop in the winter, cultivated without grazing, produces a high amount of straw, reducing weed summer infestation. Under the experimental conditions, winter soil use with pasture allows high weed summer infestation, due to the low amount of straw that stays on the soil.
