Abstract

There is need to characterize the impact of the integration crop-livestock on weed infestation in production fields; higher infestation would result in lower system sustainability mainly due to the increased demand for agrochemicals, especially herbicides. Thus, we aimed with this study to assay weed dynamics in a farmer's managed, long-term crop-livestock system, through a case study adopting the phytosociological perspective. The monitored fields measured 282 ha at the municipality of Amambai-MS, Brazil. Each area was sub-divided into two sections (“1” and “2”) for organization of quadrat distribution. A complete monitoring, which included both instantaneous infestation and soil seed bank studies, was conducted in both areas, which were managed under long-term crop-livestock integration, cycling every two years between soybean-corn succession and cattle raising (livestock). Phytosociological characterization of weed species was accomplished in 2011 based on the Ecological Approach. Estimations of relative density, frequency, dominance and Importance Value Index were obtained. Areas were also intra‑characterized by the diversity coefficients of Simpson and modified Shannon-Weiner, and then grouped by cluster analysis. Crop-livestock integration proved to be efficient in suppressing some troublesome weed species, but others still prevail in integrated production fields; for Center-West region of Brazil, pigweed, beggartick and sourgrass tend to be preponderant weed species in crop-livestock areas; weed management should go beyond cultural practices, demanding the right herbicide to be applied at the right time aiming to control the weed species which were able to prevail even in the integrated production environment.

Key words: Integrated systems, phytosociological survey, soil seed bank, crop rotation.