The researchers set up two wetlands with different plants to clean up pollution from paddy field runoff. They used synthetic wastewater with nitrogen and phosphorus as pollutants. The plant Phragmites australis was better at removing nitrogen compared to Calamagrostis angustifolia. Phragmites australis also took up more nitrogen and had higher concentrations of nitrogen and phosphorus in its biomass. Overall, Phragmites australis was more effective at cleaning up the water than Calamagrostis angustifolia.