Carbon Negative?

[Ryan Carboni]

https://en.wikipedia.org/wiki/Azolla_event
Azolla has been deemed a "super-plant" as it can draw down as much as
a tonne of nitrogen per acre per year (0.25 kg/m2/yr); this is matched
by 6 tonnes per acre of carbon drawdown (1.5 kg/m2/yr). Its ability to
use atmospheric nitrogen for growth means that the main limit to its
growth is usually the availability of phosphorus: carbon, nitrogen and
sulphur being three of the key elements of proteins, and phosphorus
being required for DNA, RNA and in energy metabolism. The plant can
grow at great speed in favourable conditions – modest warmth and 20
hours of sunlight, both of which were in evidence at the poles during
the early Eocene – and can double its biomass over two to three days
in such a climate.