Biological N2 fixation (BNF) is the largest N source in the terrestrial and ocean ecosystems, and controls the primary production and carbon-nitrogen cycling. During the last 100 years, technological innovation has broadened our understanding of microorganisms and processes, but there is much left to be discovered. Along with the population growth and climate change, greater demand for food and protein prompt the urgency to study BNF. Contributes talks could focus on 1) rates of BNF in farmland and natural ecosystems, 2) interactions between BNF and carbon-nitrogen cycling, 3) feedback of BNF to climate change, and 4) mechanisms of BNF processes including signalling, nitrogenase and bioinorganic chemistry.