Table 1.

List of all experimental treatments conducted in this study.

Experiments
Condition (optimal and low $\mathrm{N}{\mathrm{O}}_3^{-}$)			Description
[Low ${\mathrm{P}\mathrm{O}}_4^{3-}$–Low Fe]	[Medium ${\mathrm{P}\mathrm{O}}_4^{3-}$–Low Fe]	[High ${\mathrm{P}\mathrm{O}}_4^{3-}$–Low Fe]	First experiment – optimal ${\mathrm{NO}}_3^{-}$ (4.4 mM)
[Low ${\mathrm{P}\mathrm{O}}_4^{3-}$–Medium Fe]	[Medium ${\mathrm{P}\mathrm{O}}_4^{3-}$–Medium Fe]	[High ${\mathrm{P}\mathrm{O}}_4^{3-}$–Medium Fe]	Second experiment – low ${\mathrm{NO}}_3^{-}$ (0.15 mM)
[Low ${\mathrm{P}\mathrm{O}}_4^{3-}$–High Fe]	[Medium ${\mathrm{P}\mathrm{O}}_4^{3-}$–High Fe]	[High ${\mathrm{P}\mathrm{O}}_4^{3-}$–High Fe]	Third experiment – ${\mathrm{NO}}_3^{-}$ starvation (6 nM), comparing with optimal ${\mathrm{NO}}_3^{-}$ in selected treatments
Recovery experiments
Initial treatment	Condition of $\mathrm{N}{\mathrm{O}}_3^{-}$	Nutrient added (at day 12)	Resulting treatment (maintained for 4 days)
[Low ${\mathrm{P}\mathrm{O}}_4^{3-}$–Low Fe]	Optimal ${\mathrm{NO}}_3^{-}$ (4.4 mM)	${\mathrm{P}\mathrm{O}}_4^{3-}$ and Fe	[High ${\mathrm{P}\mathrm{O}}_4^{3-}$–High Fe] in optimal ${\mathrm{NO}}_3^{-}$ treatment.
[Low ${\mathrm{P}\mathrm{O}}_4^{3-}$–Low Fe]	${\mathrm{NO}}_3^{-}$ starvation (6.66 nM)	${\mathrm{P}\mathrm{O}}_4^{3-}$, Fe, and ${\mathrm{NO}}_3^{-}$	[High ${\mathrm{P}\mathrm{O}}_4^{3-}$–High Fe] in optimal ${\mathrm{NO}}_3^{-}$ treatment.

In the recovery experiments, $P{O}_4^{3-}$, Fe, and/or ${NO}_3^{-}$ were added to the different initial treatments to achieve optimal conditions to evaluate the changes in APA rates.