关键词: 香根草, 富营养化, 水体净化

Abstract: The study on the vertical and horizontal distribution of organic matters and total nitrogen (TN) in the sediment of ditch wetland naturally grown with reed (Phragmites communis) and wild rice (Zizania latifolia) showed that the sediment below 40 cm depth had a significant effectiveness in retaining and accumulating organic matters and TN,but in its surface layer,this effectiveness varied largely with seasons,and the maximum was more than twofold of the minimum.TN was highly correlated with organic matters,the correlation coefficient being 0.9876 in reed wetland and 0.9335 in wild rice wetland,and in water phase,it was positively related to NH₄⁺-N and NO₃-N,indicating that the main composition of TN was organic N,and the mineralization of organic N was the sources of inorganic N.The harvest of reed in each autumn could take away 818 kg·hm^-2 of N and 103.6 kg·hm^-2 of P,and that of wild rice could take away 131 kg·hm^-2 of N and 28.9 kg·hm^-2 of P.Zizania caduciflora had a high assimilation ability of nutrients.Its cultivation in ditch wetland to replace wild helophytes would be a good approach to attain higher absorbing ability of N and P,and to resolve the secondary pollution problem of emerged plants,because farmers could harvest it voluntarily.

Key words: Vetiveria zizanioids, Eutrophication, Purification of water body