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Phosphorus Transport in Agricultural Subsurface Drainage: A Review
Author(s) -
King Kevin W.,
Williams Mark R.,
Macrae Merrin L.,
Fausey Norman R.,
Frankenberger Jane,
Smith Douglas R.,
Kleinman Peter J. A.,
Brown Larry C.
Publication year - 2015
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2014.04.0163
Subject(s) - tile drainage , subsurface flow , environmental science , baseflow , drainage , surface runoff , hydrology (agriculture) , ditch , tillage , water quality , watertable control , eutrophication , current (fluid) , soil water , environmental engineering , groundwater , drainage basin , streamflow , soil science , geology , nutrient , geotechnical engineering , ecology , oceanography , cartography , biology , geography , soil salinity , chemistry , organic chemistry
Phosphorus (P) loss from agricultural fields and watersheds has been an important water quality issue for decades because of the critical role P plays in eutrophication. Historically, most research has focused on P losses by surface runoff and erosion because subsurface P losses were often deemed to be negligible. Perceptions of subsurface P transport, however, have evolved, and considerable work has been conducted to better understand the magnitude and importance of subsurface P transport and to identify practices and treatments that decrease subsurface P loads to surface waters. The objectives of this paper were (i) to critically review research on P transport in subsurface drainage, (ii) to determine factors that control P losses, and (iii) to identify gaps in the current scientific understanding of the role of subsurface drainage in P transport. Factors that affect subsurface P transport are discussed within the framework of intensively drained agricultural settings. These factors include soil characteristics (e.g., preferential flow, P sorption capacity, and redox conditions), drainage design (e.g., tile spacing, tile depth, and the installation of surface inlets), prevailing conditions and management (e.g., soil‐test P levels, tillage, cropping system, and the source, rate, placement, and timing of P application), and hydrologic and climatic variables (e.g., baseflow, event flow, and seasonal differences). Structural, treatment, and management approaches to mitigate subsurface P transport—such as practices that disconnect flow pathways between surface soils and tile drains, drainage water management, in‐stream or end‐of‐tile treatments, and ditch design and management—are also discussed. The review concludes by identifying gaps in the current understanding of P transport in subsurface drains and suggesting areas where future research is needed.