Agricultural Non-Point Nitrogen Pollution Control Function by Phragmites

Riparian wetland is the major transition zone of matter, energy, and information transfer between aquatic and terrestrial ecosystems and has important functions of water purification and non-point pollution control. Using the field experiment method and isotope tracing technique, the agricultural non-point nitrogen pollution control function of Phragmites communis Trin in riparian wetlands was studied in Kouma section of Yellow River. The results show that retention of agricultural non-point nitrogen pollution by riparian wetland soil occurs mainly in the top 0-10 cm soil layer, which account for 58.89% of the total nitrogen interception. Exogenous nitrogen in the 0-10 cm soil layer changes the fastest of all layers. One month after K¹⁵NO₃ added to the surface soil, nitrogen content is 76.96% and after three months, nitrogen content is 92.84%. The nitrogen uptake amount of Phragmites communis Trin is 96.11 kg hm^-2. Observation results indicate that riparian wetlands as buffers on and adjacent to stream banks are recommended to control agricultural non-point pollution.