Strategies for research and management in reduced-input agroecosystems

Abstract

Developing reduced-input agroecosystems is a challenge to researchers and practitioners in a number of disciplines. In particular, because of the complexity of managerial inputs, understanding the effects of decreases in levels of one or several inputs presents a difficult experimental problem. Moderate reductionism is proposed as an appropriate hierarchical analysis, which first characterizes system level behavior and then explains it in terms of system components and their interactions. An example is given using reduced nitrogen fertilizer inputs; higher nitrogen use efficiency at lower levels of input is explained by increased nutrient recycling between soil and plant subsystems. Transition from conventional to reduced-input management involves changes in both economic and ecological properties of agroecosystems. Biological, chemical and physical changes, including increased species diversity, tighter nutrient recycling, and longer-term perennial effects, may parallel ecological succession. Hypothetical trends for several such changes are discussed.