Accurately quantifying rates and patterns of biological nitrogen fixation is difficult, however, due to the diversity of organisms and symbioses involved, and because rates are highly variable in space and time. Studies that quantify nitrogen fixation require foresight in planning, data interpretation, and extrapolation to ensure that measurements will best meet information needs. As part of a Powell Center synthesis led by USGS and university scientists, researchers presented a conceptual and practical road map to study design, study execution, data analysis, and scaling, with examples from the literature and sample R code. Standardizing study design at each of these stages will improve the accuracy and interpretability of data, define limits of extrapolation, and facilitate broader use of biological nitrogen fixation data in quantitative analyses and simulation models. 

Soper, F.M., Taylor, B.N., Winbourne, J., Wong, M., Dynarski, K.A., Reis, C.R., Peoples, M., Cleveland, C.C., Reed, S.C., Menge, D.N., Perakis, S.S., 2021, A roadmap for sampling and scaling biological nitrogen fixation in terrestrial ecosystems: Methods in Ecology and Evolution, https://doi.org/10.1111/2041-210X.13586