ARS | Publication request: Temporal variability of nitrogen and phosphorus transport in subsurface drainage

Submitted to: Soil and Water Conservation Society
Publication Type: Abstract Only
Publication Acceptance Date: December 24, 2008
Publication Date: July 11, 2009
Citation: King, K.W., Fausey, N.R., Smiley, P.C. 2009. Temporal variability of nitrogen and phosphorus transport in subsurface drainage [abstract]. Soil and Water Conservation Society.

Technical Abstract: Subsurface drainage is a necessity for crop production agriculture in humid climates with poorly drained soils. The Midwestern United States is the most productive agricultural area in the world. In excess of 20.6 million ha (37%) of the tillable acres in the Midwest are managed with subsurface tile. While partially responsible for consistent high crop production yields, subsurface tile drainage has been recognized as a primary source of agricultural nutrient transport to streams and waterbodies to which they discharge. While information exists about the end of tile transport of nutrients, knowledge of how that is transferred to a watershed outlet is not well understood. Surface and subsurface hydrology and nutrient samples were collected from Jan 1, 2005 to Dec 31, 2007 on a 389 ha watershed located in the Upper Big Walnut Creek Watershed, OH. One surface (watershed outlet) and six subsurface tiles ranging in size from 8 inches to 2 feet were instrumented in 2004 with weirs and automated water samplers. Preliminary results suggest that the amount of nutrient transport in tile drainage as a percentage of watershed load varies seasonally and can constitute a significant amount of the total. The findings will be beneficial in determining the timing and application of best management practices that may be beneficial in combating nutrient transport from subsurface drainage.