Simulating phosphorus loss to subsurface tile drainage flow: a review

Abstract

Agricultural land is a major source of phosphorus (P) loss, and artificial drainage is one of the pathways for phosphorus transport. In this paper, we reviewed the methods and equations related to phosphorus loss through subsurface tile drain in water quality models. This review is presented through three topics: subsurface hydrology, fate and transport of phosphorus in soil, and phosphorus transport into tile drains. Major simulation methods and some recent updates are reviewed, and calculations in specific models are presented. Nine existing water quality models (ADAPT, ANIMO, APEX, EPIC, HYDRUS, ICECREAM, MACRO, PLEASE, SWAP) can be used to simulate P transport to tile drainage, where three of them (HYDRUS, MACRO, SWAP) do not have a specific phosphorus module but P can be simulated using a general chemical module. Models that are not suitable for simulating fate and transport of P to tile drains under their current status, for example, AnnAGNPS, DRAINMOD, GLEAMS, RZWQM2, SurPhos, SWAT, are also reviewed due to their strength in one of the aspects: subsurface drainage or P dynamics. Based on the methods used in those models, ICECREAM could be the most current comprehensive model for P loss through tile drains from agricultural fields.