Weeds in soybean crop after annual crops and pasture

The use of crop practices to reduce the weed community is an ally to integrated weed management. Given this, the study aimed to identify a composition and weed infestation in a soybean area under different predecessor crops implanted in different years. The experiment was carried out in the 2019/2020 harvest in Dourados, MS. The experimental design was a randomized block with nine treatments. The treatments were composed of autumn-winter crops. The area with predecessor cultivation: corn-Brachiaria intercropping; cowpea beans; single corn; an area with predecessor cultivation of Brachiaria as pasture for one year; two years; three years; four years; five years, and six years. All treatments were followed by soybean cultivation in the 2018/2019 harvest and an intercropping with corn and Brachiaria in the 2019 off-season harvest. There was a difference in the absolute weed infestation between the evaluated areas. Treatments with corn and cowpea had greater weed infestation. However, areas with pasture or intercropping with corn and Brachiaria showed less infestation, especially in areas with Brachiaria grown in the off- season for more than two years. The weed species composition differs between the areas evaluated. The implantation of a corn-Brachiaria intercropping in the off-season under a crop rotation system, especially in areas with Brachiaria grown in the off-season for more than four years, reduces the weed infestation.