Iron, phosphorus, and nitrogen supply ratios define the biogeography of nitrogen fixation

We present a unified conceptual framework describing the competition between diazotrophs and non‐nitrogen‐fixing marine plankton and their interaction with three essential nutrient elements: nitrogen (N), phosphorus (P), and iron (Fe). The theory explains the global biogeography of diazotrophs and the observed large‐scale variations in surface ocean nutrient concentrations. The ratios in which N, P, and Fe are delivered to the surface ocean,...