Friday, August 7, 2009 - 10:30 AM

OOS 51-8: Organic vs. conventional: Weed management in the agricultural systems in the suburban areas of San Cristóbal de las Casas

Ana Elisa Pérez-Quintero, University of Puerto Rico

Herbicides are to a vast degree contrary to integrated weed management and have direct and indirect negative social and environmental effects on agroecosystems. Evidence accumulated shows that a careful diversification of the weedy component of agroecosystems can be a management strategy for the elimination of herbicide use. By evaluating and researching how “arvenses” (useful herbaceous that grow without being planted) are used in the crops and the role they have in promoting ecological diversity in the farmers’ plot we can achieve more sustainable practices. In Huitepec, a suburban farming community in San Cristóbal de las Casas Chiapas, organic and conventional farmers were interviewed about how they learn and incorporate weed management into agricultural productions. Different practices were compared to evaluate the process of production; interviews were analyzed and compared with data acquired through experimental quadrants as well as weed sampling in five organic and five conventional farms identifying the more useful weeds, their richness and uses.  Results/Conclusions .
Weeding strategies and herbicide use can vary substantially depending on local conditions. In terms of the practices organic farmers learn about weed management by what is passed down generation from generation, experimenting from their own crops and learning from other farmers. The weed diversity present in the organic fields is dominated by useful weeds, while the weed diversity in the conventional fields is dominated by those weeds that compete with the crops.  Organic farmers have hand picked those useful weeds and managed them so that competitive weeds (known as malezas) grow to a lower scale. Conventional farmers use herbicides eliminating beneficial weeds. By eliminating beneficial weeds they disturb the ecological balance in agroecosystems. The last component of the research is the necessity we found to publicize knowledge farmers have on useful weeds. This way we validate agricultural knowledge through ecological research. To do this we are starting to create a web page-database in collaboration with the farmers of the arvenses, a short documentary of the interviews and finally a comic book that explains integrated weed management.