During the 4th ESA-Congress, held in the Netherlands, 7-11 July 1996, a new perspective for agronomy emerged. Various contributions demonstrate the need for a new role of agronomy and its tools. In recent decades, agriculture has evolved from an activity with mainly productivity aims, into an issue conciliating environmental, agricultural, and economic and social objectives. Placing agriculture in such a broadened perspective requires a different agronomy, with new tools and approaches at a range of aggregration levels. It calls for detailed knowledge concerning the functioning, productivity...