AGROECOSYSTEM - LONG-TERM AGROECOSYSTEM EXPERIMENTS - ASSESSING AGRICULTURAL SUSTAINABILITY AND GLOBAL CHANGE

Long-term agroecosystem experiments can be defined as large-scale fiel d experiments more than 20 years old that study crop production, nutri ent cycling, and environmental impacts of agriculture. They provide a resource for evaluating biological, biogeochemical, and environmental dimensions of agricultural sustainability; for predicting future globa l changes; and for validating model competence and performance. A syst ematic assessment is needed to determine the merits of all known exper iments and to identify any that may exist in tropical and subtropical environments. The establishment of an international network to coordin ate data collection and link sites would facilitate more precise predi ction of agroecosystem sustainability and future global change.