Agricultural systems are no longer evaluated solely on the basis of the food they provide, but also on their capacity to limit impacts on the environment, such as soil conservation, water quality and biodiversity conservation, as well as their contribution to mitigating and adapting to climate change. In order to cope with these multiple service functions, they must internalize the costs and benefits of their environmental impact. Payments for ecosystem services are hoped to encourage and promote sustainable practices via financial incentives. The authors show that while the principle...