The book relies on the systems approach and adopts a three-perspectual view on agricultural research and development. Concepts and methodologies used in population ecology (1), agro-ecology (2) and sustainable development (3) are presented on a historical background, summarized in different categories and illustrated with case studies originating in agricultural systems positioned between industrial and human rights narratives. To deal with uncertainties and risk, adaptive governance and adaptive management of population systems and agroecosystems are recommended. To meet the current challenges of an agriculture at crossroads, incremental gains in knowledge are seen as insufficient and a rethinking of agricultural research indispensable. The book is written for agronomists and students in agronomy in particular, but the summarized concepts and methodologies are presented to satisfy the interest of a broad range of stakeholders in natural resource management.