Wednesday, November 15, 2006

Complexity and Research on the Sustainability of Farming Systems.

Stephen R. Kaffka and Theodore Foin. Univ of California, Dept of Plant Sciences, One Shields Ave, Davis, CA 95616

Key concepts in agroecology are that well-designed farming systems, especially organic ones, will be able to sustain acceptable yields and that insects and pathogens will be self-regulating. These ideas are found in formulations of organic farming principles early in the 20th century. More recently, concepts from ecology about homeostasis and system-level emergent properties attributed to natural ecosystems have also been attributed to farming systems using multifunctional crop rotations. Farming systems research seeks to replicate conditions leading to emergent properties like homeostasis and study them, but such properties have been difficult to demonstrate experimentally. Many descriptive studies of farming systems are incomplete or fail to clearly identify the bio-physical causes for system behavior. Previous efforts at studying multifunctional farming systems in Europe have generally been unsuccessful.  Systems theory suggests that there is a limit to the number of interactions and the level of complexity that can be analyzed, and that overly-specified farming systems cannot be generalized. Neither natural nor agro-ecosystems are inherently self-regulating, but are subject to a variety of external influences including climate, inputs, and interactions with other systems which vary in time and space.  We suggest that only experimental systems of limited complexity can be analyzed for emergent properties and their specific causes. Because farming systems are dynamic, only long-term experiments can assess important dynamic properties of farming systems and include then in an analytical assessment.