Integrating agronomic and economic models falls within the realm of bioeconomic models whereby biological processes under study are explicitly represented. In the case of agriculture, this approach is based, on the one hand, on an agronomic model specification of production technologies integrated to an economic model – most often of a constrained optimisation type – and on the other hand, on their impacts in terms of yields and environmental externalities. This explicit (primal) representation of technologies is well suited to study the environmental impacts of agricultural policies and represents an interesting alternative to the dual approach that is frequently used in the econometrics. It also enables ones not only to assess the effects of new agricultural policy instruments such as decoupled subsidies and agri-environmental contracts but also to take into account the non-convexities between agriculture and the environment.