Crop rotation with nitrogen-fixing legumes has proven effective in replenishing nutrient-deficient soils but evidence suggests the byproducts of these legumes have a wider influence on soil biogeochemical processes than previously thought. Root nodules are associated with symbiotic nitrogen-fixing bacteria generating hydrogen as a by-product of nitrogenase activity. In practice, 40-60 percent of electron transfers of nitrogenase are expended for hydrogen production, representing an energy investment of 5-6 percent net photosynthesis. Energy loss through hydrogen production might be a judicious investment of nitrogen-fixing plants, since diffuse sources of hydrogen were shown to exert a fertilization effect in soil. The project will help researchers understand the contribution of microbes to fundamental carbon cycling mechanisms in soil and provide novel insights into the impact of crop rotation on soil fertilization and ecosystem functioning. This research is expected to enhance the body of knowledge in biogeochemical functioning of key ecosystems, governing the global budget of carbon in the biosphere.
PI: Philippe Constant, INRS, Canada