Over 850 thousand hectacres of farmland in Missouri could benefit from the installation of subsurface drainage systems.  However, increased use of subsurface drainage systems in Missouri may result in additional P may enter surface waters via tile drainage water.  A four year subsurface drainage study was initiated on a claypan soil in corn production starting in June, 2010. The objectives of this research are to (i) determine how much ortho-P can be lost via tile drainage water and (i) determine if subsurface drainage can improve corn yield production in a claypan soil and (ii) determine if managed subsurface drainage can significantly reduce ortho-P loss in tile drainage water compared to conventional subsurface drainage. Data is currently being analyzed at this time.