Impact of Drainage Water Management on Crop Yield, Drainage Volume, and Nitrate Loss
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Subsurface drainage systems are an important component of agricultural production systems in many areas of Iowa. However, these drainage systems have been shown to deliver nitrate-N to downstream waterbodies. While subsurface drainage is important for crop production, the design of these systems to minimize nitrate-N loss also needs to be considered. Use of drainage water management in the design and operation of subsurface drainage systems is one potential method to reduce nitrate-N loss. Drainage water management may consist of drains installed at shallower depths (i.e. shallow drainage) than conventional designs, or installing water control structures at the outlet (i.e. controlled drainage). Since 2007, a study has been conducted at the Southeast Iowa Research and Demonstration Farm near Crawfordsville, Iowa, to determine the impact of shallow, controlled, conventional, and no drainage on crop yields, subsurface drainage volumes, and nitrate loss through subsurface drainage. This research investigates whether drainage water management reduces nitrate loadings to downstream surface waters, plus the yield benefits of these drainage systems.