Field examination on reed growth, harvest and regeneration for nutrient removal

A wetland where aquatic macrophytes grow is expected to have the function of water purification. Nutrients assimilated by them are removed from the water by harvesting those plants. In order to carry out harvesting to remove nutrients effectively, it is essential to know the life cycle behavior of the plants. In this study, the characteristics of reed growth and regrowth after harvest were examined in the actual field. The height and number of the shoots, the standing biomass and nutrient contents were observed. The average height of living shoots reached its maximum when total sunshine duration was 500 hours since harvest. Nutrient contents showed the maximum value in the early growth stage. On the basis of these results, the numerical simulation model about the life cycle of the aboveground part of reed was developed to investigate nutrient removal efficiency by various harvest methods. It was recommended to harvest twice a year for the effective nutrient removal.