Estimating Parameters of LEACHN in Zeolite-Amended Soil and Unamended-Soil Conditions

In this study، the effect of clinoptilolite zeolite، as a soil amendment، on the parameters related to water and nitrogen movement in soil was investigated. Parameter and uncertainty estimation in the unamended (control) and amended soil (Z)، was performed using the sequential uncertainty fitting algorithm (SUFI-2) which is linked to LEACHN (in the LEACHN-CUP software). The goodness of prediction uncertainty was judged on the basis of P-factor and R-factor. P factor، R-factor، and Nash-Sutcliffe coefficient (NS) was obtained 0. 71، 0. 76، and 0. 92، respectively، in the prediction of the accumulated drainage from control. The results in prediction of the accumulated drainage from Z treatment using hydraulic parameters obtained in control were satisfactory (P-factor = 0. 87، R-factor = 0. 78، and NS = 0. 87). P-factor، R factor، and NS were 0. 87، 1. 36، and 0. 91، respectively، in the prediction of NO3-N leaching at control. According to the P-factor and R-factor values (P-factor = 1، R-factor = 2. 46)، application of the control parameter ranges in the prediction of NO3-N leaching at Z treatment produced a large uncertainty. By adjusting the parameters in control for zeolite amended soil، the estimated values for denitrification rate، distribution coefficient، and soil/solution NO3-N nitrification rate were greater in zeolite-amended soil compared to control.