Systems thinking and practice for alley cropping research

Systemic and reductionist methodologies were applied to explore alley cropping systems. Alder (Alnus rubra) and black locust (Robina pseudoacacia) are grown as green manure in sweet corn production systems. Our research includes the study of biological, ecological, and social interactions. The overarching approach follows the Hawkesbury systems agriculture model in which interactions are explored on four levels of research. On a basic science level, we study the soil food web composition and nitrogen cycling in the plant-soil system by using a new N-15 method that involves direct injection of the tracer into xylem of the trees. Applied field research involves the response of trees and crops to various planting patterns and N equivalence trials. Optimized systems inquiry is a third level of inquiry involving modelling of alley cropping systems limited by light and nitrogen. Field data are compared with predicted tree and crop growth. Finally, human action inquiry investigates the social components of this cropping system. We use participatory appraisal techniques such as farmer-scientist focus sessions and participatory mapping to improve the farmers' ability to deal with complexity in their farming system and to learn about farmers' decision making.