Williams JR
Tanzania
Research Article
Phosphorus Modeling in Tile Drained Agricultural Systems Using APEX
Author(s): Francesconi W, Williams CO, Smith DR, Williams JR and Jeong JFrancesconi W, Williams CO, Smith DR, Williams JR and Jeong J
Phosphorus (P) losses through tile drained systems in agricultural landscapes may be causing persistent eutrophication problems observed in surface water. The purpose of this paper is to evaluate the state of the science in the Agricultural Policy/Environmental extender (APEX) model related to surface and tile P transport. This was accomplished using data from a monitored corn-soybean rotation field in the St. Joseph River watershed, IN. The estimation of soluble phosphorus (SP) in surface runoff and tile flow in APEX includes a user defined linear (based on GLEAMS) and nonlinear (Langmuir) sorption option. The results suggest that the inclusion of the Langmuir isotherm improved (18%) SP sorption estimates in surface runoff during the corn year only when P inputs were added, whereas the linear method was more appropriate during the soybean year when no fertilizers were applied. Simila.. View More»
