Nitrate Loads of Agricultural Drainage in “Boston Bay”—a Mississippi River Backwater Area and Potent

• 作 者: WANG Peifang SCHNOEBELEN Douglas J. QUARDERER Nathan A.
• 机 构: IIHR-Hydroscience & Engineering,University of Iowa,Iowa City,United States,IA 52242;Key Laboratory o
• 出 处: 第十三届世界湖泊大会
• 发表日期: 2009年7期
• 关键词: Nitrate Load Agricultural drainage Nitrogen control Boston bay Mississippi River

Agricultural nitrogen loss is the major contributor to nitrogen load in the Mississippi River,and consequently to the high level of nutrition and the existence of "hypoxia" in the Gulf of Mexico.The nitrate concentration is of high proportion compared to the total nitrogen of surface water in the United States which is of different from China.The study area was a backwater area locally named "Boston Bay" in the mid-section of the Mississippi River in eastern Iowa/western Illinois).The nitrate load from this agricultural drainage district was calculated from October,2008 till June,2009 to illustrate the effects of farm lands on the nitrogen import to Mississippi River.In addition,the data collected highlights the use of real-time nitrate sensor technology in monitoring nitrate concentrations.The impacts of agricultural subsurface(tile) drainage—a major pathway of agricultural nitrogen loss to surface water in the upper Midwest,the crop planting way,and the time of fertilization for nitrate load producing from the small agricultural watershed in Boston Bay were analyzed and discussed.For reducing nitrogen loading to the Gulf of Mexico from the Mississippi River Basin,many of strategies,policies and approaches are currently being discussed.The on-site control of agricultural drainage includes changing or varying cropping systems,reducing nitrogen fertilizer application rates,better management of the timing of nitrogen application,and better management of drainage tile systems.On the other hand,many kinds of technologies were and would be used in the agricultural drainage of Mississippi River Basin,which can be regarded as the off-site agricultural drainage treatment.Among these technologies,the construction of riparian buffers and wetlands and habitat restoration are the most important and popular methods,which can be of benefit and give some advice for nitrogen control in the watersheds of China.