Tuesday, November 14, 2006 - 4:05 PM

N Uptake Affects Corn Yield and N Loss in Tile Drains as Simulated by Agricultural System Models.

Robert Malone1, Liwang Ma1, and Ramesh Kanwar2. (1) USDA-ARS, 2150 Pammel Dr, Ames, IA 50011, (2) Iowa State Univ, Agricultural and Biosystems Engineering, 104 Davidson Hall, Ames, IA 50011-3080

The dual goals of meeting food demand while protecting the environment from excess reactive nitrogen may be one of the greatest ecological challenges facing humankind.  The complexity of this challenge will require use of agricultural systems models and one of the biggest challenges to accurately simulate crop production and nitrogen loss is to accurately predict nitrogen uptake by plants.  Annual nitrogen demand and N uptake by plants is generally much larger than N loss to subsurface drains, therefore, small errors in predicting nitrogen uptake can lead to unacceptably large errors in predicting N loss to subsurface drains.  Our objective is to quantify the sensitivity of predicted nitrate loss in subsurface drains to predicted N uptake by crops.  Strategies to minimize modeling errors will be explored.