Theory and Practice for Environmental Risk Assessment: Understanding the Trade-Off Between the Benefits and Risks Behind Herbicide Use as Tool for Designing Sustainable Weed Management Systems

Abstract

The adoption of herbicides as a weed control strategy has allowed farmers to reduce the short-term effects of biological adversities on crop yields. However, they have also jeopardized agroecosystem sustainability by causing negative alterations of social and environmental subsystems. The physicochemical properties of herbicides (volatility, adsorption, or water solubility) can make them persist in the soil, air, and water, changing the structure and function of key environmental compartments. The occurrence of herbicide-resistant weed populations has generated a positive feedback loop requiring the application of higher doses, aggravating negative externalities. Hence, the economic benefits of herbicides as a unique control strategy substantially decrease in time. In addition, the dependence of agricultural systems on external inputs generates an herbicidal “lock-in” process that hinders the transition towards more sustainable integrated management systems. Therefore, there is a pressing need to elucidate the principal aspects of environmental risk analysis of herbicide use in agroecosystems. The objectives of this chapter are: (1) to introduce key concepts related to the construction and application of environmental risk indicators with a focus on agricultural system risk assessment, (2) to list the potentially negative effects associated with the use of herbicides, (3) to understand the processes that regulate herbicides’ fate and behavior in farming systems, (4) to highlight the importance of decision support systems (DSS) in reducing herbicide use in favor of integrated weed management (IWM), and (5) to understand the decision-making logic behind the increasing adoption of chemical weed control despite its negative socio-environmental effects.