Etienne Hainzelin comes back to the striking evolutions of the agricultural systems for hundred years, particularly in the rich countries. Today, this is an intensified agriculture, based on the supply of fertilizers and pesticides, and on the use of the 'elite' varieties. This transformation, which affected as the landscapes as the functioning of the human societies, also supported the progressive emergence of questionings about the compatibility between the high-yield agriculture and the preservation of ecosystems.