Abstract
Micro-organisms can potentially supplement or replace the use of chemical fertilizers and pesticides in many agricultural cropping systems. Their increased use may reduce the need for nitrogen and phosphorus fertilizers, particularly in legume and cereal crops, and provide a more ecologically sound method of controlling pests and phytopathogens. Recombinant DNA technology offers the potential to extend and improve these applications. However, genetically modified micro-organisms may occasionally themselves pose environmental risks. Model ecosystems such as intact soil-core microcosms may be useful for both testing efficacy and evaluating environmental risk prior to proceeding with field trials.