Led by PhD student Darian Smercina, Optimization of the 15N2 incorporation and acetylene reduction methods for free-living nitrogen fixation was recently published in Plant and Soil. Using both the acetylene reduction assay (ARA) and 15N2 incorporation (15N2) method for measuring nitrogen fixation, Darian assessed the impact of different carbon sources, oxygen concentrations and incubation times on Free-Living Nitrogen Fixation (FLNF) rates. She found that a cocktail of different carbon sources greatly increased fixation as compared to other carbon sources. Highlighting the need for project specific optimization, site played a factor in optimal oxygen concentration, while both the optimal incubation time and oxygen concentration varied by method. This work also reinforces previous concerns with ARA and stresses caution when using the method. Check out the full paper for more info!