ii ACKNOWLEDGMENTS I would like to acknowledge the following for completion of this thesis: God for giving me the patience, guidance and strength to succeed in this research. I am so grateful for everything I have been given and everything I was able to do. Without God I can do nothing. Dr. Nandita Basu for challenging and guiding me throughout graduate school and this research. I have grown an...

This study was conducted to evaluate the performance of DRAINMOD /DRAINMOD-N on an experimental drainage field at Southeast Purdue Agricultural Center (SEPAC), based on the comparison between observed and predicted subsurface drain flows and nitrate-nitrogen losses via drainage. The site was under conventional drainage management, consisting of two replications of three tile drain spacings—5m, ...

Tom Scherer Extension Agricultural Engineer The presence of salts and high water tables in North Dakota soils due to an extended climactic wet cycle recently has stimulated interest in the installation of tile drainage systems. The tile controls the water table and encourages the leaching and removal of salts from the soil above the tile lines. This improves soil productivity, culminating in im...

Reducing nitrate loads from corn and soybean, tile-drained, agricultural production systems in the Upper Mississippi River basin is a major challenge that has not been met. We evaluated a range of possible management practices from biophysical and social science perspectives that could reduce nitrate losses from tile-drained fields in the Upper Salt Fork and Embarras River watersheds of east-ce...

Tile drains and French drains are typically used to control subsurface drainage, especially on greens and fairways with shallow water tables or fine soil texture. Tile drains are defined as "drains constructed by laying drain tile with unsealed joints in the bottom of a trench which is then refilled," whereas French drains are a "type of drain consisting of an excavated trench, refilled with pe...

61 S in the Gulf of Mexico have documented a large area with seasonally depleted O2 levels (<2 mg L−1). Most aquatic species cannot survive at such low O2 levels. A reduction in NO3–N loading by 30% was initially recommended to reduce hypoxia in the Gulf of Mexico (Mitsch et al., 1999). Following a scientifi c reassessment that recommended a reduction of 45% (USEPA, 2007), the USEPA developed a...

Background The separation of runoff components within a model simulation is of great importance for a successful implementation of management measures. Diatoms could be a promising indicator for tile drainage flow due to their diverse preferences to different aquatic habitats. In this study, we collected diatom samples of 9 sites (4 tile drainage, TD, and 5 river sites, Ri) in a German lowland ...

Ž . y Nitrogen N in surface waters has been linked to agricultural crop production, and more specifically, to NO exported 3 Ž by tile drainage. The objective of this study was to evaluate agricultural N pools and fluxes in a seed cornrsoybean Zea . Ž . y maize L.rGlycine max L. watershed 40 ha to relate soil inorganic N pools with annual losses of NO in drainage tiles. 3 During a 2-year period ...