Tile Drains As Non-Growing Season Conduits for P Losses.

Tile drains are part of the agricultural landscape in most humid areas, and particularly in the Great Lakes basin.  Their presence affects movement of water and movement off the land both during the growing season, and outside of it.  Recent advances in our understanding of the partitioning of tile water between matrix and macropore flow will be discussed, and the implications of this for the export of both nitrate and phosphorus from agricultural land into surface water.