Task: Text Categorization
Input (English): Phytoplankton with very high levels of this element are called "survivalists" because they are better at acquiring scarce resources. Agropyron repens dominated areas high in this element in experiments by David Tilman, which found that early successional species are better at acquiring it. The partner choice and sanctions hypotheses can explain a symbiosis centering around this element. Plants produce leghemoglobin to avoid oxygen poisoning of an enzyme that processes this element. Diazotrophs are able to survive without external sources of this element, and in oceans, the anammox process decreases its availability. This is the most commonly limiting element in terrestrial ecosystems, but most legumes have rhizobial root nodules capable of fixing it into ammonium. For 10 points, name this element whose diatomic form makes up 78% of the Earth's atmosphere.
Output (English): Science