614 Abstract Most phosphorus (P) modeling studies of water quality have focused on surface runof loses. However, a growing number of experimental studies have shown that P losses can occur in drainage water from artifcially drained felds. In this review, we assess the applicability of nine models to predict this type of P loss. A model of P movement in artifcially drained systems will likely need to account for the partitioning of water and P into runof, macropore fow, and matrix fow. Within the soil profle, sorption and desorption of dissolved P and fltering of particulate P will be important. Eight models are reviewed (ADAPT, APEX, DRAINMOD, HSPF, HYDRUS, ICECREAMDB, PLEASE, and SWAT) along with P Indexes. Few of the models are designed to address P loss in drainage waters. Although the SWAT model has been used extensively for modeling P loss in runof and includes tile drain fow, P losses are not simulated in tile drain fow. ADAPT, HSPF, and most P Indexes do not simulate fow to tiles or drains. DRAINMOD simulates drains but does not simulate P. The ICECREAMDB model from Sweden is an exception in that it is designed specifcally for P losses in drainage water. This model seems to be a promising, parsimonious approach in simulating critical processes, but it needs to be tested. Field experiments using a nested, paired research design are needed to improve P models for artifcially drained felds. Regardless of the model used, it is imperative that uncertainty in model predictions be assessed. Applicability of Models to Predict Phosphorus Losses in Drained Fields: A Review David E. Radclife,* D. Keith Reid, Karin Blombäck, Carl H. Bolster, Amy S. Collick, Zachary M. Easton, Wendy Francesconi, Daniel R. Fuka, Holger Johnsson, Kevin King, Mats Larsbo, Mohamed A. Youssef, Alisha S. Mulkey, Nathan O. Nelson, Kristian Persson, John J. Ramirez-Avila, Frank Schmieder, and Douglas R. Smith A rtificial drainage, either in the form of surface ditches or subsurface tile drains, is a prerequisite for efcient crop production in many areas of the world. Globally, about 12.3% of cropland has been drained, but there is considerable variation in this proportion (Table 1). Drained cropland is concentrated in areas of poorly or imperfectly drained soils, in temperate climatic zones where seasonal variations result in soil moisture accumulation during winter, and where mecha- nized agriculture dominates. In areas like the Great Lakes basin, the proportion of drained land can approach 65%, primarily as tile drainage (Pavelis, 1987). Impact of Artifcial Drainage on Hydrology Poorly drained soils are characterized by slow subsurface water movement, shallow water table depth, frequent surface water ponding, and surface runof. Tese soils are usually fne textured with low hydraulic conductivity and/or a shallow impervious or semi-impervious soil layer restricting groundwater downward movement to the underlying aquifer. Artifcial drainage signifcantly alters feld hydrology and consequently has a large impact on the fate and transport of sediment, nutrients, and pesticides in drained cropland. Compared with natural drainage conditions, artifcial drainage lowers water tables, Abbreviations: DP, dissolved phosphorus; DRP, dissolved reactive phosphorus; MCS, Monte Carlo simulation; PP, particulate phosphorus; TP, total phosphorus; USLE, Universal Soil Loss Equation. D.E. Radclife, Crop and Soil Sciences Dep., Univ. of Georgia, Athens, GA 30602; D.K. Reid, Agriculture and AgriFood Canada, 174 Stone Road W, Guelph, ON, Canada N1G 4S9; K. Blombäck, H. Johnsson, M. Larsbo, K. Persson, and F. Schmieder, Swedish Univ. of Agricultural Sciences, Dep. of Soil and Environment, P.O. Box 7014, SE-750 07 Uppsala, Sweden; C.H. Bolster, USDA–ARS, Food Animal Environmental Systems Research Unit, 230 Bennett Ln, Bowling Green, KY 42104; A.S. Collick, Pasture Systems and Watershed Management Research Unit, USDA–ARS, University Park, PA 16802; Z.M. Easton and D.R. Fuka, Dep. of Biological Systems Engineering, 303 Seitz Hall, Virginia Tech, 155 Ag Quad Lane, Blacksburg, VA 24061; W. Francesconi, National Soil Erosion Research Laboratory, West Lafayette, IN; K. King, USDA–ARS Soil Drainage Research Unit, 590 Woody Hayes Drive, Columbus, OH 4321; M.A. Youssef, Dep. of Biological and Agricultural Engineering, North Carolina State Univ., D.S. Weaver Laboratory, Campus Box 7625, Raleigh, NC 27695; A.S. Mulkey, Dep. of Environmental Science and Technology, Univ. of Maryland, College Park, MD 20742; N.O. Nelson, Kansas State Univ., Agronomy Dept., 2708 Throckmorton Plant Sciences Center, Manhattan, KS 66506-5501; J.J. Ramirez-Avila, Civil and Environmental Engineering Dep., Mississippi State Univ., Mississippi State, MS 39762-9546; D.R. Smith, Grassland, Soil and Water Research Laboratory, 808 East Blackland Road, Temple, TX 76502-6712. Assigned to Associate Editor Peter Kleinman. Copyright © American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. 5585 Guilford Rd., Madison, WI 53711 USA. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. J. Environ. Qual. 44:614–628 (2015) doi:10.2134/jeq2014.05.0220 Received 17 May 2014. Accepted 10 Dec. 2014. *Corresponding author (dradclif@uga.edu). Journal of Environmental Quality PHOSPHORUS FATE, MANAGEMENT, AND MODELING IN ARTIFICIALLY DRAINED SYSTEMS SPECIAL SECTION Published March 11, 2015